Regular sleep schedule: why regularity matters alongside duration

General information, not medical advice. If you are often tired despite enough hours of sleep, or have been sleeping badly for a long time, discuss it with your GP.

When you think about sleeping well, you usually think about the number of hours, but timing counts too. A regular sleep schedule means you go to bed and get up at roughly the same time every day, including days off. Say you go to bed at 11 pm on Wednesday, at 2 am on Saturday, and sleep in until 11 am on Sunday. Your sleep tracker may still count eight hours, and yet you can feel tired.

Regularity and sleep duration: what a large study found

The American Academy of Sleep Medicine (AASM) and the Sleep Research Society recommend at least seven hours of sleep per night for adults aged 18 to 60. According to the AASM, good sleep also requires appropriate timing and day-to-day regularity. You will find reference values by age in the sleep checklist for training weeks.

Windred and colleagues (2024) followed 60,977 participants in the UK Biobank, a large British health study, with an average age of almost 63. For one week they wore a movement sensor on the wrist, from which a regularity score was derived: 100 means someone slept and was awake at exactly the same hours every day, 0 a random pattern. The researchers divided them into five equal groups. During an average follow-up of just over six years, the four more regular groups had a 20 to 48 percent lower risk of dying than the least regular group, taking into account age, lifestyle and health, among other factors. Regularity predicted that risk better than sleep duration. It remains an association and not a demonstrated cause, and according to the authors a single week of measurement is only a snapshot.

Chaput and colleagues (2020) brought together 41 studies in a systematic review, a study that combines all available research on a question: later sleep timing and more variable sleep times were mostly associated with poorer health. They could not determine a threshold above which sleep times vary too much, and the quality of the evidence ranged from very low to moderate.

Social jetlag: when your week and your weekend drift apart

Wittmann and colleagues (2006) call the difference between your sleep times on work days and free days social jetlag. It arises when your working hours clash with your body clock, the internal rhythm that determines when you feel sleepy and when you are awake. Evening types in particular build up a sleep shortage during the week that they catch up on during free days.

In Chaput’s review, social jetlag was associated with poorer health, but weekend catch-up sleep with better health. A National Sleep Foundation panel (Sletten and colleagues, 2023) concludes that regular sleep times are important for health and performance, and that some extra sleep on free days may help if you sleep too little during the week.

How to build a regular sleep schedule

Gezond Leven, the Flemish institute for health promotion, advises going to bed at roughly the same time, only getting into bed when you feel sleepy, and getting up at the same time as much as possible. Your wake-up time is therefore the fixed point. Choose a time you can manage on most days, including Saturday, and work back from there to your bedtime. The US National Heart, Lung, and Blood Institute advises limiting the difference between weekdays and weekends to about an hour. Your evening counts too, especially if your bedtime shifts later because of a screen before sleep.

Light also plays a part. Phillips and colleagues (2017) followed 61 American students for a month. In the most irregular sleepers, the release of melatonin, the hormone that makes you sleepy in the evening, started on average only at 00:08, compared with 21:32 in the most regular sleepers. According to the researchers’ computer model, this was probably mainly due to a different pattern of light exposure across the day.

What a sleep tracker does and does not tell you

A sleep tracker can show how much your sleep times vary. Baron and colleagues (2017) describe patients who, because of their tracker data, believed they were sleeping badly and ended up in a perfectionistic quest for ideal sleep, which they call orthosomnia. So use such a device to follow your rhythm, not to chase a score. If you train a lot, also look out for signs of too little recuperation.