Time, energy and life paths / Chapter 3
This section only counts energy and time. It looks at four things: how much attention you can use each day, how fast you react, how many mistakes you make, and how long it takes to get back after an interruption. Most figures are measured directly, from experiments or from tracking a group of people over time. These numbers are not converted into lifespan or mortality. Most items in this section have evidence grade B. That is how this field is; it does not mean the advice fails. Item 19 is about expectations when dealing with police, doctors, and bank tellers; it cites regulations, not experiments, so its grade is C. Item 15 (treat pessimistic thoughts as a symptom) and item 22 (treat “others expect me to be perfect” as a symptom) cite mortality and suicide-risk figures. Their frame differs from the rest of this section; do not compare them side by side.
Items are grouped by theme below, with item numbers in parentheses.
Attention at work: Turn off non-essential notifications (item 1), batch-process messages each day (item 5), block brief interruptions (item 6), do one thing at a time (item 7), use earplugs in open offices (item 12), and do not keep adding weekly work hours for their own sake (item 13).
Sleep and staying up: Keep a fixed wake-up time (item 2), get 7 to 8 hours of sleep each night (item 3), avoid caffeine after 2 p.m. (item 4), skip glowing screens for the hour before bed (item 8), go to bed on time (item 9), make no major decisions late at night (item 10), take a 10-minute nap when drowsy in the afternoon (item 11), try cognitive behavioral therapy for insomnia first for long-term insomnia (item 26), and get checked for sleep apnea if you snore, stop breathing in sleep, or are sleepy by day (item 27).
Thoughts in the head: Switch to a hands-on task when you keep replaying something (item 14), treat pessimistic thoughts as a symptom (item 15), halve your estimate when you feel you looked foolish (item 21), and treat “others expect me to be perfect” as a symptom (item 22).
Anger and low mood: Leave first when angry (item 17), do a few high-value things first when mood is low (item 18), do not vent anger by punching a bag (item 23), and write what is on your mind for several days in a row (item 24).
People and social media: Learn to decline requests you do not want (item 16), treat police and doctors as people who work by rules (item 19), and set limits on apps that show peers’ feeds (item 20).
Pain in the body: For period pain, take an ibuprofen-type painkiller (item 25).
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. …
For the most irregular fifth of people, the body clock runs about 2.5 hours later than for the most regular fifth. That is like living with jet lag all the time. Students with more regular schedules also get better grades.
Two weeks in a row of only 6 hours a night, and brain performance falls to about the level of two full nights with no sleep. The problem is you do not feel it. …
Taking 400 mg of caffeine 6 hours before bed, about three or four cups of coffee, showed up on instruments as more than 1 hour less sleep that night. A sleep diary you write yourself shows no difference at all. …
The same group of participants was studied over two weeks. …
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. …
As soon as you switch tasks, reactions slow and mistakes become more likely. People who often use several kinds of media at once have not trained themselves to do several things at once; they do worse on task-switching tests.
Reading a glowing screen before bed, versus a paper book, delays falling asleep by about 10 minutes. Melatonin is suppressed by 55%. The next day’s body clock shifts more than 1. …
In 2025 Chinese people averaged 6.97 hours of night sleep and fell asleep at 0:10 on average. Among children and teens, those who used a phone or tablet before bed were more than twice as likely to get too little sleep, and 2. …
When well slept, people quickly learn to avoid high-risk options. After two nights in a row with no sleep, they keep picking the high-risk ones instead; the older they are, the clearer this is. …
When the previous night was short, a 10-minute nap lifts alertness right away; some of that effect lasts about two and a half hours. A 5-minute nap is basically useless. A 20-minute nap only shows benefit after 35 minutes. …
When background noise rises from 39 dB to 51 dB, people remember fewer words, feel more tired, and are less motivated to work. …
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. …
Replaying the same bad episode deepens depression, nails negative thoughts in place, makes problems harder to solve, and makes real action harder. It also wears out people around you who would listen. …
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. …
In a survey of widowed women aged 60 to 89, unpleasant contacts linked to well-being more strongly and more consistently than pleasant ones. So cut first, then add.
Looking at what just happened from another angle, or standing in the other person’s place for a moment, both bring the emotion down; the second works better. Simply not showing the emotion also has a little effect. …
Brisk walking, jogging, yoga, and strength training all ease depression; higher intensity works better. Details are in Section 22, Item 6 (when mood is bad, walk or run). …
Police, doctors, and bank tellers are people who work by post rules, bound by paperwork, deadlines, and oversight. How many days a matter should take, and what document you get if it cannot be done, are written in the rules. …
People who habitually compare themselves to others online tend to feel worse emotionally and have lower self‑esteem. …
Walk in wearing an awkward T-shirt and you think nearly half the people can tell who is printed on it; actually fewer than a quarter can. Switch to a decent T-shirt and you still overestimate the same way. …
People who keep feeling “people around me demand I be perfect, and if I fall short I will be rejected” are more likely to have suicidal thoughts. …
Punching a bag, cycling, or going for a run — ways of venting that amp the body up — generally do not cool anger. Slow breathing, mindfulness, and meditation — ways that settle the body — clearly cut anger and the urge to strike.
Writing down a bad experience has a small average benefit. Pooled conclusions also disagree; two pooled analyses found no clear effect. It costs almost nothing, so you can try it. …
For period pain, ibuprofen-type drugs raise the share with clearly less pain from under two in ten to about half. They work better than acetaminophen, with a bit more side effects. …
After this treatment, falling asleep is about 19 minutes faster on average, and time awake in the night drops about 26 minutes. Effects slowly weaken, but they are still there at 12 months. …
Sleep apnea means breathing stops or gets shallow in waves during sleep; you wake gasping and are sleepy by day. After CPAP, daytime sleepiness drops clearly, and driving crashes fall by about seven tenths. …
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