10 sleep hygiene rules

Getting up at the same time every day, weekends included, is the single most useful rule. Your wake-up time, more than your bedtime, is what sets your internal clock. A big gap between weekdays and weekends creates "social jet lag": Monday morning feels like flying home from a trip. Your bedtime can shift a little depending on how tired you are; keep your wake-up time as steady as you can.

To fall asleep, your body needs to cool down slightly. A bedroom that's too warm gets in the way and leads to more awakenings. Air the room, turn the heat down, and use a fan in summer. A warm bath or shower one to two hours before bed helps too: warming the skin helps your body shed heat afterward.

Light, even dim light, holds back melatonin, the hormone that signals nighttime. Blackout curtains or a sleep mask often make a real difference. Watch out for the small lights you no longer notice: TV standby lights, chargers, alarm clocks. Blue light suppresses melatonin the most; warm, amber light is far less disruptive.

In a Harvard study, reading on a tablet in the evening instead of a printed book made people take longer to fall asleep, lowered their melatonin, shifted their internal clock and left them less alert the next morning. Ideally, turn off screens a while before bed. If you can't, turn the brightness all the way down and use night mode. For reading in bed, paper is still the best choice.

Caffeine blocks adenosine, the molecule that builds up your need for sleep over the day, and its effect lasts for hours. According to the European Food Safety Authority, 100 mg (about one espresso) taken close to bedtime can be enough to disturb sleep in some people. Sensitivity varies a lot: if you sleep poorly, stop by early afternoon. Caffeine is in coffee, black and green tea, colas, energy drinks, chocolate and some pain relievers.

Alcohol can help you drift off, but it wrecks the second half of the night: less REM sleep, more awakenings, a faster heart rate, night sweats. If you have sleep apnea, it's worse still, because it relaxes the muscles of the throat and makes apneas more likely. One or two drinks in the evening are enough to make a difference.

Regular physical activity helps you sleep better: you fall asleep more easily and sleep more deeply. And despite what many people think, evening exercise doesn't ruin your night: a review of 23 studies found no harmful effect in healthy adults. Only a very hard workout right before bed may delay sleep. If that's you, simply move your session earlier.

Your brain learns by association. Doing the same things in the same order every night tells it that sleep is on the way. A warm shower, a few pages of a paper book, slow breathing, quiet music: what you do matters less than doing it every night.

This is the idea behind stimulus control, one of the tools of cognitive behavioral therapy for insomnia (CBT-I). Working, watching shows or scrolling your phone in bed teaches your brain that bed is a place for being awake. If you're still awake after about twenty minutes, without checking the clock, get up, do something calm in another room, and only go back once you feel sleepy. The one exception to bed-is-for-sleep: sex.

Racing thoughts at bedtime are one of the main reasons people struggle to fall asleep. A few habits can help break the loop: in the early evening, jot down what's on your mind and what you'll do tomorrow, breathe slowly for a few minutes, or try mindfulness. If stress or anxiety takes hold, working with a psychologist is still the most effective answer.