Protecting Your Mental Energy

Even if you don’t look at or touch your phone when it rings, your performance on attention‑related tasks still drops. The drop is roughly the same as when you actually answer calls or send messages. Another scenario: even when the phone sits on the desk and you resist the urge to glance at it, the amount of mental capacity available still decreases. The more dependent a person is on their phone, the greater this drop tends to be.

Cost

No cost at all. It takes just a few minutes to adjust the settings, and hardly any willpower is required.

Benefit

Merely receiving a notification — without looking at or interacting with the phone — noticeably impairs performance on attention tasks. The degree of impairment is comparable to actually answering calls or sending messages. These findings come from laboratory studies involving university students. Two additional experiments also show that even when participants successfully refrain from looking at their phone, having it nearby still reduces their available mental resources; this effect is strongest among heavy phone users.

Note

All of these results are based on single‑task experiments conducted in a lab setting. No research has examined how these effects accumulate over days or weeks in real‑world conditions. For jobs where immediate responsiveness is essential, it may be advisable to allow notifications only from a limited set of contacts.

For the top 20% of students with the most irregular sleep schedules, their circadian rhythm runs roughly 2.5 hours later than that of the top 20% with the most regular schedules. This is equivalent to living with a persistent jet lag. Moreover, students with more consistent sleep patterns tend to achieve better academic results.

Cost

No cost involved. Sticking to this on weekends requires a bit of willpower.

Benefit

Sixty-one university students tracked their sleep patterns over 30 days. The group with the least regular schedules had a circadian rhythm that lagged by about 2.5 hours compared to the most regular group — specifically, the time when melatonin starts secreting was 00:08 versus 21:32 for the latter. The period when they felt most sleepy also occurred roughly 1.8 hours later. Additionally, greater sleep regularity correlated with better academic performance, with a correlation coefficient of r = 0.37.

Note

This is the sole study on this topic, with a relatively small sample size and no control groups. Researchers estimate that these circadian differences stem mainly from varying daily exposure to natural light. Therefore, maintaining a fixed wake-up time works best when paired with exposure to morning sunlight. For tips on how to recover after occasional late nights, see Section 2, Item 39: the recommended approach is to go to bed earlier that very night rather than sleeping in until noon the following day.

After two full weeks of getting only 6 hours of sleep each night, brain performance drops to a level equivalent to going two full nights without any sleep at all. The tricky part is that people don’t notice this effect themselves. Their self-rated sleepiness only rises during the first few days and then plateaus — people sleeping 6 hours report the same level of fatigue as those sleeping just 4 hours. In other words, the belief that “6 hours of sleep is enough for me” is actually a symptom of chronic sleep deprivation.

Cost

No cost at all. You simply need to set aside 1–2 extra hours each day for sleep. Going to bed earlier requires a bit of willpower.

Benefit

In a randomized controlled trial, 48 healthy adults aged 21–38 were asked to get just 6 hours of sleep per night for 14 consecutive days. Their cognitive performance steadily declined, eventually reaching levels comparable to those seen after two full nights of total sleep loss. Meanwhile, their self-reported sleepiness only increased at first and then remained largely unchanged. There was no difference in self-rated fatigue between the 6-hour and 4-hour sleep groups. Additionally, a meta-analysis of 70 studies found that acute sleep deprivation (lasting no more than 48 hours) leads to a moderate drop in simple attention (effect size g = -0.776) and a much smaller decline in reasoning accuracy (g = -0.125).

Note

The most important takeaway is that “not feeling sleepy” is not proof that you’ve gotten enough sleep. People who regularly sleep just 6 hours simply get used to the state, but their actual performance does not improve. The results from the meta-analysis apply to staying awake for an entire night; there is only one randomized controlled trial supporting the idea that consistently getting less than 6 hours of sleep has any real negative impact.

Consuming a large cup of coffee containing 400 mg of caffeine 6 hours before bedtime reduces measured total sleep time by over 1 hour, yet personal sleep logs show no difference. To avoid any impact on sleep, a regular cup of coffee (107 mg of caffeine) must be consumed at least 8.8 hours prior to bedtime; for those going to bed at 11 p.m., 2 p.m. marks the cutoff point.

Cost

No cost involved. People accustomed to drinking coffee in the afternoon must summon some willpower to abstain.

Benefit

Intake of 400 mg of caffeine 6 hours before sleep results in a measurable reduction of 1.1–1.2 hours in total sleep time compared to placebo consumption. Multiple studies combined via meta-analysis indicate that caffeine on average shortens total sleep duration by 45 minutes and lowers sleep efficiency — the proportion of time spent actually asleep while in bed — by 7%.

Note

The sole study by Drake utilized a relatively high caffeine dose of 400 mg, equivalent to roughly two or three cups of coffee, and was conducted in a single laboratory setting. Individuals with slower caffeine metabolism must adhere to an even earlier cutoff time. This recommendation complements the third item, which advises aiming for 7–8 hours of sleep nightly.

The same group of participants was studied over two weeks. During the week when they limited email checks to just three times per day, their daily stress levels dropped noticeably compared to the unrestricted week — while the total number of emails sent and received stayed the same. Without any limits, people checked their emails an average of 15.5 times per day.

Cost

No monetary cost. However, it takes some time to explain to colleagues how often you’ll be checking messages. It also requires a bit of willpower to resist the urge to check them constantly.

Benefit

In a two-week self-controlled trial involving 124 adults, those who limited email checks to three times daily experienced significantly lower daily stress than when they checked freely (effect size: Cohen’s d = 0.37). The overall volume of emails received and replied to did not differ between the two conditions. Without restrictions, participants checked emails 15.5 times per day on average.

Note

Only one study has examined this approach, showing a modest effect size. It measured stress levels rather than actual work output. No direct research exists on limiting instant messaging checks; this recommendation is extrapolated from similar email studies.

Even a brief interruption lasting 2.8 seconds on average doubles the chance of errors in subsequent steps of a sequential task. An interruption of 4.4 seconds triples that error rate. Field observations also show that it takes an average of 25 minutes to return to the interrupted task, with two other unrelated tasks squeezed in during that time. People who get interrupted do finish tasks faster, but they report higher levels of stress, frustration, effort, and time pressure.

Cost

No cost at all. Just close the door, put on headphones, or hang a “Do Not Disturb” sign.

Benefit

On average, a 2.8-second interruption doubles the error rate for sequential tasks, while a 4.4-second interruption triples it. This finding comes from lab experiments. Another study observed 24 office workers (information professionals) in real-world settings. They switched topics every 11 minutes on average, and 57% of those topic switches were interrupted. It took them 25 minutes and 26 seconds on average to get back to the interrupted task, with 2.26 other tasks added in between. A separate experiment with 48 participants showed similar results: interrupted workers completed tasks faster, but reported significantly higher stress, frustration, effort, and time pressure.

Note

The field study mentioned above categorized interruptions into two types: those caused by others approaching the worker, and those initiated by the worker themselves. Simply closing the door blocks only the first type of interruption. To handle the second type, combine this tip with Tip 1 (turn off non-essential notifications) and Tip 5 (batch-process messages).

Every time you switch tasks, your reaction time slows down and errors become more likely. People who regularly keep multiple screens open at once don’t actually get better at multitasking; in fact, they perform worse on task-switching tests.

Cost

No cost at all. It does take a bit of willpower to resist replying to messages during a meeting.

Benefit

Switching between tasks clearly slows reaction time and raises the chance of mistakes. This conclusion comes from a review of multiple studies. One lab study involved university students. Those who frequently use several types of media at the same time are known as heavy media multitaskers. They’re more easily distracted by unrelated things and unrelated memories, and they also perform worse on task-switching tests.

Note

Exactly how much extra effort task-switching requires varies a lot depending on the task, so no single number can be given here. The Ophir study compares people at one single point in time, so it’s hard to tell whether multitasking makes attention worse, or whether people with poorer attention skills simply prefer to multitask.

Reading from glowing screens before bed delays sleep onset by roughly 10 minutes compared to reading paper books. It also lowers melatonin production by 55%. The next day, the body’s internal clock shifts more than 1.5 hours later, making mornings harder and requiring extra time to feel fully awake.

Cost

No cost involved. Giving up phone use one hour before bed requires willpower, especially when fighting long-standing habits.

Benefit

In controlled lab experiments, the same participants were tested under both conditions (cross-over design). Those reading from glowing e-readers fell asleep about 10 minutes later than those reading paper books (25.7 minutes versus 15.8 minutes). Their nighttime melatonin levels dropped by 55%, and their circadian rhythm shifted by over 1.5 hours — melatonin secretion started at 22:31 instead of 21:01. This resulted in greater morning sleepiness and a longer recovery time to full alertness.

Note

The study involved a small number of participants and was conducted under tightly controlled lab conditions. Real-world effects may be smaller given typical phone brightness and usage patterns. The study did not evaluate how much nighttime screen modes actually help.

In 2025, Chinese people slept an average of 6.97 hours per night, with an average bedtime of 12:10 a.m. Those who used phones or tablets before bed were more than twice as likely to get insufficient sleep and 2.7 times more likely to feel drowsy during the day. Even simply having such devices in the bedroom — without using them — produced similar results. Thus, keeping phones out of the bedroom is the simplest way to improve sleep.

Cost

No monetary cost. The real challenge is overcoming the habit of “just one more episode.” The easiest solution is to keep phones out of the bedroom.

Benefit

In 2025, Chinese residents averaged 6.97 hours of nighttime sleep, with an average bedtime of 12:10 a.m. (Chinese Sleep Research Society). Compared to people who did not use portable devices before bed, those who did were 2.17 times more likely to get insufficient sleep (OR 2.17), 1.46 times more likely to suffer poor sleep quality (OR 1.46), and 2.72 times more likely to feel daytime drowsiness (OR 2.72). Even merely having devices in the bedroom without use yielded similar odds: 1.79, 1.53, and 2.27 respectively (OR 1.79/1.53/2.27). These figures come from a combined analysis of 20 concurrent surveys involving 125,198 children and adolescents. Another concurrent study of 844 adults aged 18–94 found that those who used phones after turning off the lights took longer to fall asleep, spent less time actually asleep in bed, and felt more fatigued during the day.

Note

This recommendation is somewhat controversial. The overall risks of chronic sleep deprivation are covered in section 3 of this chapter (aiming for 7–8 hours of sleep per night). Currently there is no reliable evidence linking porn to reduced energy or cognitive ability in the general population. One meta‑analysis suggests that so‑called “porn problems” often stem from a mismatch between personal beliefs and behavior rather than from the content itself. Another study of 280 men found no correlation between the amount of time spent watching porn and erectile function during sexual activity with a partner. This recommendation specifically addresses how porn consumes sleep time. The figures of 6.97 hours and 12:10 a.m. are taken from a Health News report republished by the Fujian Provincial Health Commission, as no official release from the Chinese Sleep Research Society was found at the time of writing (September 2026).

People who stayed awake for 49.5 hours were asked to take part in risk decision experiments. When well-rested, they quickly learned to avoid high-risk options; after sleep deprivation, they repeatedly chose high-risk choices instead. The older a person is, the more pronounced this effect becomes. This study looked at the extreme scenario of two consecutive sleepless nights; it did not directly test how much impact a few fewer hours of sleep would have, but the overall trend supports postponing important decisions until the next day.

Cost

No cost at all. You simply postpone these tasks until after you’ve woken up.

Benefit

Thirty-four healthy participants completed the Iowa Gambling Task after going 49.5 hours without sleep. This task is a standard way to measure risk decision making. When well-rested, they quickly learned to steer clear of high-risk options; after sleep loss, they opted for high-risk choices far more often. Older participants showed a stronger response to this effect. This is the only study of its kind to date. The total number of participants was 34.

Note

The research focused on the extreme case of two nights of continuous sleep deprivation. There is no direct data on how ordinary people fare after staying awake until 2 a.m. The advice to avoid sending messages late at night is based on the authors’ personal experience (rated as Grade C evidence); it is perfectly fine to send such messages the following day instead.

A 10‑minute nap gives an immediate boost of alertness that lasts about two and a half hours. A 5‑minute nap provides almost no benefit, while a 20‑minute nap only starts to help after roughly half an hour. Sleeping 30 minutes brings on sleep inertia — you’ll feel groggy right after waking, making performance worse than if you hadn’t napped at all.

Cost

It costs nothing. Just set aside 10 minutes and find a place where you can lie down or recline.

Benefit

After a night of insufficient sleep, a 10‑minute nap quickly reduces drowsiness, fatigue, and improves energy and mental performance; some of these effects persist for up to 155 minutes. A 5‑minute nap yields virtually no benefit, and the advantages of a 20‑minute nap appear only after 35 minutes. A 30‑minute nap first causes sleep inertia, so performance is actually poorer right after waking, before any improvement occurs.

Note

Only one laboratory study exists, and its participants were healthy young adults. If you can’t fall asleep, there’s no need to force it; there’s no research showing any benefit from simply lying down with eyes closed for 10 minutes. Naps longer than an hour have been linked to higher mortality and increased risk of coronary heart disease — see Section 2, Item 38 (keep naps under 30 minutes). 〔37〕

When background noise rises from 39 dB to 51 dB, people remember fewer words, feel more tired, and are less motivated to work. Watching nature videos with sound during breaks helps restore energy far better than continuing to endure office noise.

Cost

Earplugs cost just a few dozen yuan. Booking a quiet meeting room takes some time and effort.

Benefit

Students working in simulated open offices showed similar effects: at 51 dB LAeq background noise, they recalled fewer words, rated themselves as more fatigued, and felt less inclined to keep working. Viewing nature videos with audio during breaks also boosted their energy levels more effectively than listening to river sounds or office noise alone.

Note

Only one laboratory study exists on this topic. Among all noise types, speech that can be clearly understood has the greatest negative impact on performance. White noise headphones may help mitigate this effect, but they were not tested in this research.

Records from British munitions factories during World War I show that when workers kept weekly hours under 49, output rose in direct proportion to the time spent working. Once they exceeded 49 hours, the growth rate began to drop. Output from workers putting in 70 hours per week was practically identical to that of those working 56 hours — those extra 14 hours yielded no additional results. In total, this data covers a period spanning 100 years.

Cost

You might earn less in overtime pay. You may also need to put in effort to negotiate with your supervisor.

Benefit

Data from British munitions factories in World War I demonstrates that output rises steadily with working hours up to 49 per week. After that threshold, the rate of growth slows. Peak output is reached at roughly 63 hours. At 70 hours, output remains essentially the same as at 56 hours, meaning those extra 14 hours are wasted effort.

Note

These figures come from factories a century ago where most workers were women performing manual labor. This threshold may differ for cognitive work; the authors themselves note that other occupations could have higher or lower limits. What is reliable, though, is the overall trend: beyond a certain point, adding more hours yields almost no extra output. The specific figure of 49 hours is not proven.

Endlessly dwelling on the same bad memory won’t yield any answers. It only deepens depression, cements negative thoughts, makes it harder to solve problems or take action, and can drive away friends who’d otherwise listen. As soon as you realize you’re stuck in this cycle, get busy with a physical task.

Cost

No cost at all. The hard part is first recognizing that you’re stuck in this loop – a skill that takes practice.

Benefit

A review of multiple studies shows that repetitive rumination on distressing events worsens depression. This pattern, known as rumination, also strengthens negative thinking and weakens problem‑solving abilities. It hampers real‑world action and can alienate supportive people. It is linked to anxiety, binge eating, alcohol misuse, and self‑harm.

Note

This is the hardest item in this section to quantify; the review only provides general direction. “Doing something else” reflects the author’s own approach. The literature supports one core idea: diverting attention is better than staying trapped in rumination. No research has compared which specific activities work best.

In a 20-year twin study, each additional step up on a pessimism scale correlated with a roughly 13% higher risk of dying during that period, and a roughly 20% higher risk of dying from cardiovascular disease. Conversely, higher optimism scores did not bring any comparable benefits. Thus, the focus should be on reducing pessimism, not on simply “being more positive.”

Cost

No cost involved. The hard part is viewing such thoughts as symptoms rather than as objective truths.

Benefit

This study followed 2,978 twins aged 50 or older in Australia for an average of 20 years; 1,068 of them died over that time. For each standard deviation increase on the pessimism scale, the relative risk of death rose by about 13% (hazard ratio 1.134). The 95% confidence interval for this figure is 1.065–1.207, with a p-value of 8.85×10⁻⁵. Cardiovascular mortality rose by roughly 20% (hazard ratio 1.196; 95% CI 1.045–1.368; p=0.0093). No link was found between pessimism and cancer mortality. Similarly, higher optimism scores showed no meaningful association with mortality rates.

Note

This finding remains somewhat controversial. It is purely observational and no subgroups were defined. Some argue that illness might precede and cause heightened pessimism; the authors counter that if that were true, pessimism should also correlate with cancer mortality. Nevertheless, other unmeasured factors could still be at play. Importantly, optimism does not offer any protective effect, so there is no need to force oneself to “think positively.” What matters is refraining from treating pessimistic expectations as accurate forecasts of the future.

The harm caused by a draining person is greater and more consistent than the benefits brought by a supportive one. That is why it makes sense to first reduce such relationships before trying to add healthier ones.

Cost

No monetary cost. In the short term, this may cause social friction and possibly lead to losing some relationships. It also takes considerable willpower to actually say no.

Benefit

A survey of 120 widowed women aged 60–89 found that unpleasant interactions showed a stronger and more consistent link to lower psychological well‑being than pleasant ones. In other words, the negative impact of a draining person outweighs the positive effects of a supportive one.

Note

The study group is quite specific, and the questionnaire was administered only once, so no cause‑and‑effect sequence can be determined. It measures overall happiness rather than energy levels. The author includes this example as a speculative inference. There is no objective definition of what counts as a “draining” relationship; each person must judge that for themselves.

Reframing what just happened or trying to see things from the other person’s perspective can genuinely lower emotional intensity; the latter approach works especially well. Simply suppressing emotions has no effect. Additionally, people who punish those who offend them end up dwelling on the incident far longer afterward; those who do not retaliate move on more quickly. People also tend to overestimate how satisfying revenge actually is.

Cost

No cost at all. You must resist the urge to retort on the spot, turn around and leave, then decide later whether to address the situation. This takes some practice.

Benefit

A meta-analysis combining 306 separate experiments shows that reframing events (cognitive reappraisal) yields a moderate effect size of d = 0.36 on emotional intensity. Viewing things from the other person’s perspective produces an even stronger effect, d = 0.45. Distraction yields d = 0.27. Simply suppressing emotions has virtually no effect, with d = -0.04. Three other experiments likewise reveal that people who punish offenders keep thinking about them far longer; those who refrain from retaliation move on more quickly. People consistently overestimate how gratifying revenge truly is.

Note

The portion of this analysis dealing with emotional intensity — not energy expenditure — shows effects ranging from small to moderate. Because only one experiment addresses the issue of revenge, the overall grade is B. The “empty boat” parable originates from Zhuangzi’s “Mountain Trees”: one remains calm when an empty boat bumps into them, but becomes angry when a boat carrying people does the same; the impact is identical in both cases. This is purely an analogy, not empirical evidence. If actual harm has occurred, following the legal procedures outlined in Sections 8 and 9 is far less costly than reacting impulsively on the spot.

Extensive clinical trial data confirm that brisk walking and running produce the strongest benefits for depression, with yoga and strength training also helpful — the greater the intensity, the better the effect. Bright light therapy works very well for seasonal depression and also helps with non‑seasonal cases. Online self‑guided cognitive‑behavioral therapy programs are effective; having a therapist guide you makes them even better, especially if your symptoms are moderate to severe. When you’re feeling overwhelmed, dial 12356 first.

Cost

Costs little to nothing. Just a few brisk walks, runs, or strength workouts each week. Spend time outdoors in daylight or bright light. Keep a regular sleep schedule. When you’re feeling stuck, give someone a call.

Benefit

This meta-analysis combined data from 218 randomized controlled trials involving 14,170 participants; the control group performed other activities. Compared with them, walking or running lowered depression scores by g = -0.62 (95% CI -0.80 to -0.45). Yoga produced g = -0.55 and strength training g = -0.49; higher intensity further improved outcomes. Pooled data from multiple light‑therapy studies showed an effect size of 0.84 (0.60–1.08) for seasonal depression and 0.53 (0.18–0.89) for non‑seasonal cases. Another analysis aggregated individual‑patient data from various studies on internet‑based cognitive‑behavioral therapy; both self‑guided and therapist‑supervised programs outperformed controls, with therapist guidance yielding better results for moderate‑to‑severe depression (PHQ‑9 score >9). The 12356 hotline provides nationwide psychological support for at least 18 hours each day.

Note

These measures serve as adjuncts for mild‑to‑moderate depression. Individuals with moderate‑to‑severe depression or suicidal thoughts should seek professional care; they may also call 12356 first (see Section 1, Item 25). Most exercise trials involve relatively few participants and cannot employ the placebo blinding used in drug studies. Light‑therapy research available up to 2003 also includes limited sample sizes. The advice to “stick to a schedule” and “talk to someone” reflects the authors’ experience rather than specific published evidence. Remember, even a ten‑minute walk counts as “getting active” for someone dealing with depression.

Children tend to think “police exist to catch bad guys; doctors exist to heal people.” Adults should instead view these professionals as employees bound by job rules, paperwork, deadlines, and oversight. How friendly they are has little bearing on whether your task gets done or how quickly. What matters is obtaining receipts, noting deadlines, and filing appeals through proper channels — not winning an intellectual debate.

Cost

No expense involved. You only need to adjust your expectations and the sequence of actions. The first step is to resist the urge to “convince the other party with logic.”

Benefit

Switching to this approach means moving from “pleading, getting angry, and reiterating your grievances” to “handling paperwork, tracking deadlines, and appealing via official routes.” The time saved comes from eliminating endless back‑and‑forth discussions and mental re‑processing. This is a one‑time mindset shift rather than a daily time‑saving trick. The deadlines themselves serve as concrete checkpoints, all clearly stated in official documents. For public‑security cases, the investigation period may not exceed 30 days; for especially complex cases, an extension of another 30 days can be granted with higher‑level approval. If a complaint is dismissed, the notification must be delivered within three days; the complainant may request a review within seven days, after which police must issue a decision within 30 days. A further appeal to a higher authority can be filed within another seven days.

Note

Grade C is assigned because there is no scholarly source supporting the premise that “many people treat front-desk staff as archetypes rather than ordinary workers.” The only evidence lies in the rules themselves: deadlines, paperwork, and appeal mechanisms are all explicitly codified. All figures cited here originate from Chapter 8, Rule 39, which outlines procedures following a police report. This entry does not promise to “guarantee success” by following the rules, nor does it address “unfriendly attitudes” on the part of officials. It merely shifts expectations and the initial course of action. The same logic applies to bank tellers and government service windows: their actions are documented, subject to review, and accountable for errors. Therefore, the proper steps are to keep receipts, request written confirmations, and file complaints through official channels — rather than speculating about whether someone might “take advantage” of you. Legitimate priorities are laid out in law; for example, emergency care is allocated based on medical severity, not on first-come-first-served order (see Chapter 24, Rule 8 on triage). If you wish to thank a doctor who helped you, send a thank-you letter or leave a satisfaction rating as described in Chapter 24, Rule 11. Offering gifts to law-enforcement personnel to “get better service” constitutes bribery, a crime with severe statutory penalties (see Chapter 8, Rule 40). Any obvious discrimination should be reported and monitored, not imitated as an unwritten norm.

People who habitually compare themselves to others online tend to feel worse emotionally and have lower self‑esteem. Pooled clinical findings show a consistent correlation between upward social comparison and poorer psychological outcomes. Correlation does not equal causation, but randomized trials back this link: after four weeks without Facebook, participants reported a slight rise in happiness. Another study limited three major platforms to 10 minutes per day; after three weeks, loneliness and depression both declined. The trade‑off? Knowledge of current events also dropped during those four weeks of abstinence.

Cost

This costs nothing. Setting time limits or deactivating an account takes just a few minutes. The real challenge is resisting the urge to open these apps again later on.

Benefit

The combined results of 54 independent studies — 94 effect sizes and a total N of 36,583 — analyzed via a three‑level random‑effects model reveal that upward social comparison correlates with poorer mental health (average r = 0.330, 95% CI 0.289–0.370). Specific effects include higher fear of negative evaluation (r = 0.438), anxiety (0.382), depression (0.306), lower happiness (0.268) and lower self‑esteem (0.263). Life satisfaction increased by 0.12 standard deviations, while happiness rose by 0.08 standard deviations. Age, cultural background and data collection year do not alter this link. In a randomized trial of 2,743 U.S. Facebook users, 61% would accept a four‑week suspension at a cost of under $102; those in the suspension group gained 0.09 standard deviations in overall life satisfaction. Compared with typical psychological interventions (which raise happiness by ~0.34 SD and cut depression by ~0.23 SD), this effect is roughly 25–40% of that magnitude. After the trial ended, former suspension users still spent 0.31 fewer standard deviations per day on Facebook. Even after the trial ended, former suspension users still spent 12 fewer minutes per day on Facebook. A smaller trial of 143 college students showed similar benefits after limiting three platforms to 10 minutes daily. Additionally, knowledge of current affairs declined by 0.19 standard deviations, and political polarization fell by 0.16 standard deviations as a result of reduced app usage.

Note

The correlation findings merely indicate that these patterns tend to appear together; they do not prove causation. The randomized trials do suggest causal links, but they involve U.S. participants prior to the 2018 midterm elections, so applying the results directly to Chinese users is a stretch. The undergraduate trial involved only 143 subjects, limiting its statistical power. Overall effect sizes remain modest, so cutting off these apps alone will not resolve all emotional issues. This advice targets usage aimed at monitoring how others are faring; it does not apply to staying in touch with family, seeking information or job hunting. If strict limits prove hard to maintain, start by disabling push notifications, “people you may know” suggestions and homepage recommendations. For broader screen‑time management, see sections 4.15 and 4.16 (hard caps on short‑video apps and scrolling news). When feeling down, consider the actions outlined in section 19 (exercise, sunlight and regular sleep). For those seeking identity through purchases, see section 6.23; those striving to “move up a social rung” should review section 6.24.

When walking into a room wearing an embarrassing T-shirt, people assume roughly half of onlookers recognize who is on the shirt, when in reality fewer than a quarter notice. They similarly overestimate when wearing a respectable T-shirt. After group discussions, people overestimate how noticeable their verbal missteps were to others, and after casual chats, people consistently underestimate how much the other person liked them. When you feel like “everyone saw me make a fool of myself,” the actual number of people who noticed is typically only half or less.

Cost

No cost at all. It simply requires asking yourself once, when you’re nervous: “Did they really see it?”

Benefit

Experiment 1: Participants donned T-shirts featuring Barry Manilow’s portrait and entered rooms with other subjects. On average, they predicted that 46% of observers would correctly name the figure on the shirt; the actual correct rate was 23%, precisely half the estimate. Subtracting the observed rate from the predicted one yields an average over-estimation of 23 percentage points (95% CI 9–38). Excluding two sessions with only two or three observers leaves a difference of 27 points (11–43). Experiment 2: Participants wore T-shirts they personally selected as "positive." Their average prediction was 48%, whereas the true recognition rate fell to 8%. Across three additional contexts—strangers paired for conversation, college roommates, and adult workshop participants—people systematically underestimated both how much their interlocutor liked them and how much they enjoyed the talk. The authors term this the "liking gap." It appears in conversations of any length and persists for months among new roommates.

Note

Grade B reflects that all studies were conducted in laboratory or campus settings with relatively small sample sizes, involving wearing shirts or chatting with strangers. There is no direct evidence that these findings apply to situations such as being discussed by colleagues or making a mistake in a meeting. The numbers merely indicate the direction and approximate magnitude of overestimation; they do not provide a fixed multiplier you can apply. This advice is not meant to imply that others' opinions are irrelevant. In genuine evaluation contexts—interviews, defenses, assessments, or medical evaluations—judgments are real and should be taken seriously. It specifically addresses that everyday feeling of "everyone is watching me"; the real opponent here is your own estimation bias.

The correlation between the feeling of “people around me expect me to be perfect and will reject me if I fail” and suicidal thoughts is 0.28. When the phrasing changes to “I myself expect myself to be perfect,” the correlation drops to just 0.10. The real risk does not come from having high standards per se, but from perceiving those standards as being imposed by others. Even after accounting for pre-existing suicidal thoughts, the former feeling still helps predict an increase in such thoughts over time.

Cost

No cost involved. The hard part is viewing this thought pattern as something that needs addressing rather than as an accurate reflection of others’ actual expectations.

Benefit

A comprehensive meta-analysis was conducted using data from 45 studies involving 11,747 participants — including undergraduates, medical students, community members, and psychiatric patients — analyzed via a random-effects model. The weighted average correlation with suicidal thoughts is as follows: for perfectionistic concerns (a composite of socially prescribed perfectionism, fear of making mistakes, self-doubt, and perceived gaps between personal performance and standards), r =.28 (95% CI.24–.32; based on 42 studies with 7,936 participants). Socially prescribed perfectionism alone also shows r =.28 (.25–.32; 30 studies, 3,640 participants). Perfectionistic striving — which reflects self-directed perfectionism and personal standards — has a lower correlation of r =.10 (.07–.13; 31 studies, 4,588 participants). Parental criticism correlates at r =.20 (.11–.29). Regarding suicide attempts, perfectionistic concerns correlate at r =.12 (.07–.17; 15 studies, 5,275 participants), while socially prescribed perfectionism shows r =.19 (.08–.29; 8 studies, 689 participants). Even after adjusting for pre-existing suicidal thoughts, socially prescribed perfectionism still shows a modest positive link to later increases in suicidal thoughts; no such link is observed for self-directed or other-oriented perfectionism.

Note

This item is graded B because most included studies relied on single-time surveys, making it hard to establish temporal sequence. The correlation strength is moderate (r ≈.28), accounting for only a few to ten percent of total variance. Since the outcomes measured are suicidal thoughts and attempts rather than actual mortality, the overall benefit is rated as limited due to reliance on surrogate endpoints. The authors themselves note that the data on perfectionistic concerns and suicide attempts may suffer from publication bias, with studies showing weaker or null results less likely to be published; even after accounting for such missing studies, the overall trend remains unchanged. This recommendation does not oppose setting high standards; rather, it emphasizes where those standards originate and whether failure to meet them leads to feelings of personal worthlessness. Similar to the idea discussed in Item 15 — viewing pessimistic expectations like “things will definitely get worse” as symptoms — this pattern can also be addressed clinically. If you or someone you know is experiencing suicidal thoughts, call 12356 immediately and remove any means of self-harm, as outlined in Section 1, Item 25. For guidance on how to respond when someone close expresses such thoughts, refer to Section 8, Item 15. Information on depression screening for children can be found in Section 30, Item 8.

Activities that rev up the body — like punching a bag, throwing things, or going for a run — generally don’t help you cool off. On the other hand, techniques that calm the body, such as slow breathing, mindfulness, and meditation, noticeably reduce anger and the urge to lash out.

Cost

No cost at all. When you’re angry, try a few minutes of activities that slow your heart rate: breathe slowly, sit down, and quiet your mind. It’s hard to resist the urge to vent right then and there.

Benefit

A meta-analysis of 154 studies involving 184 sample groups and 10,189 participants shows that calming techniques like deep breathing, mindfulness, and meditation lower both anger and aggression. The effect size was g = -0.63, with a 95% CI ranging from -0.82 to -0.43. This result held true across genders, races, ages, and cultures. In contrast, activities that increase physical arousal — such as punching a bag, jogging, or cycling — showed virtually no effect; their effect size was g = -0.02, with a 95% CI from -0.13 to 0.09. The authors conclude that neither venting anger nor going for a run is an effective way to defuse it.

Note

These findings measure anger and aggression, not overall energy levels. The authors categorize the time spent on calming activities as “minutes saved from dealing with fallout after an argument.” Immediate techniques you can use right now include the “circular sighing” method described in Section 22, Item 9, and “stepping away when angry” in Rule 17 of this section. Running isn’t useless in the long run — it helps ease low mood, as noted in Section 22, Item 7 (“When feeling down, go for a walk or run”). It simply isn't a good short-term fix for anger. While angry, avoid driving, sending messages, or making important decisions. If someone is physically attacking you, leave the scene and call the police; your priority then is safety, not emotional regulation — see Section 8, Item 43 (“If you’re being abused”).

Writing about upsetting matters generally provides a small benefit on average, though the results are inconsistent. Two meta-analyses found no effect at all. Since it costs almost nothing, it’s worth trying. However, if emotional problems are severe, it should not replace professional medical care.

Cost

This costs nothing. Typical practice in studies is to write 3–4 times, each session lasting 15–20 minutes. Write about something that bothers you and express your deepest thoughts and feelings.

Benefit

One meta-analysis combined data from 146 randomized studies in which participants wrote or spoke about personally important topics. On average, the effect was positive and statistically significant, though very small (effect size r =.075). Another meta-analysis limited to randomized controlled trials found no significant effects on either physical or mental health across 30 trials. For 16 trials involving cancer patients and survivors, there were no significant improvements in psychological, physical, or quality-of-life outcomes; the effect size for psychological outcomes was g = 0.04, with a 95% confidence interval ranging from –0.06 to 0.14.

Note

This approach remains controversial. Proponents point to the 146-study meta-analysis showing a small positive effect, while critics cite two meta-analyses of randomized controlled trials that found no significant benefits. The recommended frequency and duration of writing sessions come from the original experimental designs, as summarized in Mogk’s meta-analysis. This method is included here because it requires virtually no expense or time and can be done alone. It may be useful when someone has no one to talk to about their problems. The time-based measurement used here reflects how authors categorized effort levels. If writing becomes increasingly distressing, stop and dial 12356, as described in Section 1, Item 25.

For primary menstrual cramps (dysmenorrhea), over-the-counter NSAIDs like ibuprofen increase the proportion of women achieving moderate-to-excellent pain relief from under 20% to roughly 50%. They are significantly more effective than acetaminophen, with slightly more mild stomach side effects. If pain is severe enough to miss work or school, causes deep pelvic pain during intercourse, or fails to respond after 3 months of medication, consult a gynecologist to evaluate for endometriosis, which takes an average of 6.7 years to be formally diagnosed.

Cost

A box of over-the-counter ibuprofen costs a few dollars, taken only during symptomatic days. If clinical evaluation is required, outpatient consultation and pelvic ultrasonography take half a day and standard copay costs.

Benefit

A Cochrane systematic review pooled 80 randomized controlled trials comprising 5,820 women with primary dysmenorrhea (menstrual pain without identifiable pelvic pathology). Compared to placebo, nonsteroidal anti-inflammatory drugs (NSAIDs) were substantially more effective for pain relief (OR 4.37, 95% CI 3.76–5.09): while only 18% of women on placebo achieved moderate to excellent pain relief, 45% to 53% on NSAIDs achieved relief. Adverse effects were moderately higher with NSAIDs (OR 1.29, 95% CI 1.11–1.51), affecting 11% to 14% of NSAID users versus 10% on placebo, predominantly mild gastrointestinal discomfort (OR 1.58) and transient nervous system effects (OR 2.74). Compared directly with acetaminophen (paracetamol), NSAIDs demonstrated superior pain reduction (OR 1.89, 95% CI 1.05–3.43 across 3 trials), with no clear efficacy differences among specific NSAID molecules. Updated 2024 National Institute for Health and Care Excellence (NICE) guidelines advise suspecting endometriosis in women (including adolescents aged 17 and under) who present with persistent pelvic pain, period pain that impairs daily activities and quality of life, deep pain during or after sexual intercourse, painful bowel movements or urination during menstruation, or unexplained subfertility associated with any of these symptoms. NICE recommends an initial 3-month trial of first-line analgesics (acetaminophen or NSAIDs); if symptom control remains inadequate, prompt specialist gynecological referral is recommended. Crucially, a completely normal pelvic examination and normal ultrasound do not exclude endometriosis. In a prospective multicenter study across 16 hospitals in 10 countries involving 1,418 women undergoing diagnostic laparoscopy, the diagnostic delay between initial symptom onset and surgically confirmed endometriosis averaged 6.7 years, primarily driven by delayed primary care recognition. Women with confirmed endometriosis reported an average weekly loss of 10.8 productive hours, predominantly through impaired on-the-job performance (presenteeism). A nationwide Dutch survey of 32,748 women aged 15–45 found that 13.8% had taken formal sick leave due to menstrual symptoms (mean 1.3 days per year), while 80.7% reported presenteeism, culminating in an average loss of 8.9 productive workdays per woman annually.

Note

Individuals aged 60 and older, those with past gastrointestinal bleeding, or those currently taking anticoagulants or systemic corticosteroids must consult a physician prior to using NSAIDs (detailed in Chapter 34, Rule 3). FDA drug labeling notes that ibuprofen may cause severe allergic reactions, particularly in individuals with aspirin sensitivity; those with active asthma should seek medical advice beforehand. Never self-administer NSAIDs after 20 weeks of gestation due to fetal renal risks (detailed in Chapter 34, Rule 5). For individuals who cannot tolerate NSAIDs, acetaminophen is a suitable alternative (observe daily maximum dosage limits in Chapter 34, Rule 1). Pain medication for dysmenorrhea is taken acutely during the first few days of menstruation; it does not reach the monthly medication-overuse headache threshold (15 days per month) described in Chapter 34, Rule 9. Grade A reflects high-volume randomized trials. Benefit magnitude is categorized as Moderate based on the symptom reduction and restored daily functionality. Primary beneficiary is yourself.

Completing cognitive behavioral therapy for insomnia reduces sleep onset latency by an average of roughly 19 minutes and cuts nocturnal wakefulness by about 26 minutes. Although benefits slowly attenuate over time, meaningful improvements persist at 12 months. Digital self-guided courses deliver outcomes comparable to in-person clinical sessions. Sedative-hypnotic sleep medications offer modest benefits in older adults: for every 6 older adults taking sleeping pills, 1 experiences adverse effects, whereas only 1 in 13 experiences improved sleep.

Cost

Undertaking CBT-I through hospital sleep clinics, psychiatry, or clinical psychology departments involves registration and therapy session fees; online digital CBT-I courses are considerably less expensive. A complete course typically runs 6 to 8 weeks, requiring a daily sleep log. Stimulus control techniques can be implemented immediately at home: go to bed only when sleepy; get out of bed if awake after ~20 minutes; reserve the bed strictly for sleep and sex; maintain a consistent wake time seven days a week; avoid daytime naps. The most challenging component is sleep restriction therapy: initially restricting time in bed to match actual sleep duration induces transient daytime sleepiness during early weeks.

Benefit

Diagnosis and treatment specifications for mental disorders issued by the National Health Commission of China (2020) define chronic insomnia according to international criteria: (1) difficulty initiating sleep, difficulty maintaining sleep, or early morning awakening; (2) daytime fatigue, cognitive impairment, or social/occupational dysfunction; and (3) symptoms occurring at least 3 nights per week for at least 3 months (symptoms under 3 months are classified as short-term insomnia). Guidelines designate CBT-I as the first-line intervention, comprising five core elements: sleep restriction, stimulus control, cognitive restructuring, relaxation training, and sleep hygiene education, generally structured across 6 to 8 weekly sessions. National guidelines indicate CBT-I produces short-term efficacy comparable to pharmacological treatment, with superior long-term durability, and recommend pharmacotherapy generally not exceed 4 consecutive weeks without formal monthly reassessments. The American College of Physicians (ACP, 2016) strongly recommends all adult patients receive CBT-I as initial treatment for chronic insomnia disorder, with adjunctive short-term medication considered only if CBT-I alone proves inadequate. A systematic review and meta-analysis pooling 20 randomized controlled trials (1,162 participants) found CBT-I reduced sleep onset latency by 19.03 minutes (95% CI 14.12–23.93), decreased wakefulness after sleep onset by 26.00 minutes (95% CI 15.48–36.52), and increased sleep efficiency by 9.91% (95% CI 8.09%–11.73%), with a non-significant change in total sleep time (+7.61 minutes, 95% CI -0.51 to 15.74) and zero reported adverse events. Another meta-analysis of 30 randomized controlled trials evaluated long-term durability: compared to untreated controls, symptom reduction exhibited effect sizes of Hedges' g = 0.64 at 3 months, 0.40 at 6 months, and 0.25 at 12 months, maintaining clinical significance up to one year. For internet-delivered digital CBT-I (dCBT-I), a meta-analysis of 11 randomized trials (1,460 participants) found effect sizes across sleep parameters ranging from g = 0.21 to 1.09, demonstrating parity with face-to-face therapy, particularly when paired with extended sessions and automated feedback. A large trial of 1,711 participants comparing dCBT-I against sleep hygiene education showed marked improvements in sleep-related quality of life and modest gains in daytime functional and psychological health. Regarding sedative-hypnotics, a BMJ meta-analysis pooling 24 randomized controlled trials in 2,417 older adults (aged >=60) taking sedatives for >=5 consecutive nights found medication increased total sleep time by 25.2 minutes and reduced nocturnal awakenings by 0.63. However, the number needed to harm (NNH) was 6 (95% CI 4.7–7.1), while the number needed to treat (NNT) for sleep improvement was 13: sedative users faced 4.78 times the odds of cognitive impairments (OR 4.78, 95% CI 1.47–15.47) and 3.82 times the odds of daytime psychomotor fatigue (OR 3.82, 95% CI 1.88–7.80).

Note

Stimulus control rules derive from American Academy of Sleep Medicine (AASM) 2021 guidelines. Sleep restriction restricts in-bed duration to actual baseline sleep duration, progressively expanding as sleep efficiency exceeds 85–90%; AASM cautions that temporary daytime somnolence during initial weeks poses risks for drivers and heavy machinery operators, and sleep restriction should be used cautiously or under medical supervision in patients with bipolar disorder, uncontrolled epilepsy, or pre-existing severe daytime sleepiness. Providing generic sleep hygiene advice alone is ineffective and explicitly not recommended by guidelines as monotherapy. Occasional poor nights do not constitute insomnia disorder: stabilize wake times (Chapter 3, Rule 2), restrict afternoon caffeine (Chapter 3, Rule 4), and eliminate illuminated screens before bed (Chapter 3, Rule 8). Patients who snore heavily or experience breath-holding must first rule out obstructive sleep apnea, detailed in Chapter 3, Rule 27. Insomnia comorbid with persistent low mood is covered in Chapter 3, Rule 18. Benefit magnitude is rated Moderate: nocturnal sleep latency and wakefulness savings total ~45 minutes nightly, accumulating to hours weekly, though total sleep duration changes little. Melatonin is ineffective for chronic insomnia, detailed in Chapter 6, Rule 34. Primary beneficiary is yourself.

Obstructive sleep apnea (OSA) causes repeated airway collapse during sleep, resulting in oxygen drops, frequent micro-arousals, and severe daytime somnolence. Adhering to nocturnal CPAP therapy markedly alleviates daytime sleepiness and reduces motor vehicle crash risk by roughly 70%. However, randomized trials have not demonstrated that CPAP lowers cardiovascular mortality or prolongs lifespan; the primary objective of treatment is restoring daytime alertness and daytime cognitive function.

Cost

Involves consultation at a sleep center, pulmonology, or ENT clinic. Diagnostic polysomnography (overnight sleep study) is conducted in-hospital or via home sleep apnea testing devices. For moderate-to-severe disease requiring continuous positive airway pressure (CPAP), purchasing a medical CPAP machine represents a significant out-of-pocket expense ($400–$1,200). The primary hurdle is behavioral persistence: wearing a nasal or oronasal mask nightly takes weeks to adapt, and many patients discontinue use after a few hours per night.

Benefit

The American Academy of Sleep Medicine (AASM) 2017 diagnostic guidelines identify high pretest probability for moderate-to-severe OSA when persistent daytime sleepiness occurs alongside at least two of the following: loud habitual snoring, witnessed breath-holding or choking during sleep, or diagnosed hypertension. Formal diagnosis requires objective overnight monitoring (polysomnography or home testing), not subjective questionnaires alone. An apnea-hypopnea index (AHI) >=5 events per hour with symptoms, or AHI >=15 events per hour regardless of symptoms, establishes diagnosis. An AASM systematic review and meta-analysis of 38 randomized controlled trials found CPAP reduced Epworth Sleepiness Scale (ESS) scores by 2.4 points (95% CI 1.9–2.8) compared to sham/control. In minimally sleepy patients across 5 trials, ESS reduction was only 1.0 point, deemed clinically insignificant by authors. The same review pooled 10 pre-post intervention studies: CPAP reduced motor vehicle crash rates to 0.3 times baseline (RR 0.3, 95% CI 0.2–0.4), an approximate 70% reduction in crashes. A 2010 meta-analysis of 9 studies found an identical crash risk reduction (RR 0.28, 95% CI 0.22–0.35), noting daytime vigilance improved within one night and driving simulator performance improved within 2 to 7 days. Untreated OSA patients had 1.21 to 4.89 times the crash risk of healthy drivers. Regarding cardiovascular and mortality outcomes, the landmark SAVE randomized controlled trial tracked 2,717 patients aged 45–75 with moderate-to-severe OSA and established cardiovascular disease for a mean 3.7 years: composite cardiovascular events occurred in 17.0% of CPAP patients versus 15.4% of usual care patients, showing no significant difference (HR 1.10, 95% CI 0.91–1.32). Mean CPAP adherence was 3.3 hours per night; CPAP significantly improved snoring, daytime sleepiness, mood, and quality of life. A 2017 JAMA meta-analysis pooling 10 randomized trials (7,266 participants) similarly found CPAP had no statistically significant effect on all-cause mortality (RR 1.13, 95% CI 0.99–1.29) or major cardiovascular events. A 2019 global Lancet study estimated ~176 million Chinese adults aged 30–69 have OSA (23.6% prevalence), with ~65.5 million having moderate-to-severe OSA (8.8% prevalence), the highest absolute volume globally.

Note

Controverted regarding cardiovascular mortality prevention. Randomized trials conclusively demonstrate that CPAP does not reduce hard cardiovascular endpoints or extend lifespan; SAVE participants were minimally sleepy at baseline and achieved average nightly use of 3.3 hours, but stratified meta-analyses by hours of use also showed no difference. Crash risk reductions come from pre-post observational cohorts rather than randomized trials, where treated drivers may have practiced greater caution. The USPSTF (2022) found insufficient evidence to recommend screening asymptomatic adults. Therefore, individuals without snoring or daytime sleepiness do not need screening. Benefit magnitude is categorized as Moderate: ESS reductions reflect meaningful alertness improvements, and crash prevention confers major safety value. If feeling fatigued while driving, pull over immediately (Chapter 1, Rule 9). Excessive daytime napping warrants evaluation (Chapter 2, Rule 37). Managing chronic insomnia is covered in Chapter 3, Rule 26. Primary beneficiaries are yourself, vehicle passengers, and fellow road users.