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The Clocks Go Back on 25 October: What It Does to Your Sleep
The clocks go back one hour at 2am on Sunday 25 October 2026, the night is an hour longer, and for most people sleep settles into the new time within a few days: the research finds that the spring change, when the hour is lost, is the one that costs sleep.1,2,3 The catch is that your body clock does not read the kitchen clock. It follows dawn, so for the first few mornings you are likely to wake at your old time, now an hour earlier by the clock, and to feel sleepy an hour before your usual bedtime.
When do the clocks go back in 2026, and do you really get an extra hour of sleep?
In the UK the clocks go back one hour at 2am on the last Sunday in October, which in 2026 is 25 October, and forward one hour at 1am on the last Sunday in March. The hour-ahead period is British Summer Time; the winter clock is Greenwich Mean Time. The clocks next go forward on 28 March 2027 and back on 31 October 2027.1 At 2am BST the clocks become 1am GMT, so the hour between 1am and 2am happens twice; 2am does not become 3am. By the clock, sunrise and sunset both move an hour earlier: lighter mornings, darker evenings.
The extra hour is real on paper: bed and up at your usual clock times and you have spent an hour longer in bed. Whether you sleep it is another matter: your body wakes at the time it is used to, now an hour earlier by the clock, so for many adults the hour shows up as a 5am start rather than a lie-in. In a 2007 study that tracked 50 people for eight weeks around each change, the timing of sleep and of daily activity readily adjusted to the autumn release from summer time,2 so the early mornings pass within days.
What does a one-hour shift do to your body clock?
The body clock sits in the brain and is set each day mainly by light, above all morning light; it runs on sun time, not clock time. In a survey of 55,000 people, the timing of sleep on free days tracked the seasonal progression of dawn under standard time but not under daylight saving time, and the authors concluded that the circadian system does not adjust to daylight saving time.2 That is why autumn is the easier direction: going back to GMT returns the clock to the time the body has been tracking all summer, and on Monday the sun rises an hour earlier by the clock, precisely the signal the body clock uses to set itself.
Which change is worse for sleep, spring or autumn?
Spring. A 2025 systematic review of 27 studies in people aged 6 to 85 found that the transition into daylight saving time was associated with shorter and poorer sleep and more sleepiness, most evident in evening chronotypes, though the authors note that inconsistent methods limit firm conclusions.3 In the eight-week tracking study, the timing of activity did not adjust to the spring change, especially in late chronotypes, while both sleep and activity adjusted readily in autumn.2
What does the evidence say about accidents and mood around the change?
The accident data are American. Across 732,835 fatal road crashes recorded in the United States between 1996 and 2017, the spring change raised the risk of a fatal crash by 6%, most in the morning, and the rise faded over the following week; the autumn change had no effect on fatal crash risk.4
Mood is a question of the season rather than the hour. The NHS describes seasonal affective disorder as a type of depression that usually happens in the winter, lists "being more tired and sleeping more than usual" among its symptoms, says it is thought to be linked to reduced levels of daylight in winter, and advises seeing a GP if you think you might have it.9 The clock change does not cause it, but it is the weekend the evenings go dark. In over 400,000 UK Biobank adults, who reported a median of 2.5 hours a day outdoors in daylight, each extra hour outdoors was associated with greater ease of getting up (odds ratio 1.46 to 1.49), less frequent tiredness (0.80 to 0.82), fewer insomnia symptoms (0.94 to 0.97), an earlier chronotype and lower odds of low mood; the study is observational, so it shows association, not cause.5
Why does the British Sleep Society want to stop changing the clocks?
In a position statement published in October 2024, the British Sleep Society concluded that circadian and sleep health are affected negatively by enforced changes of clock time, especially in the forward direction, and positively by natural daylight in the morning, and recommended that the UK abolish the twice-yearly change and keep Standard Time, which is GMT, all year.6 Permanent summer time would instead push every winter sunrise an hour later by the clock, removing the morning light the body clock depends on. The UK still changes its clocks twice a year.
How do you adjust in the days before and after the clocks go back?
Two findings shape the plan: regularity and morning light. In 61 students tracked for 30 days, the most irregular sleepers' melatonin onset came at 00:08 against 21:32 in the most regular, a gap attributed mainly to their light exposure;7 in 60,977 UK Biobank adults wearing wrist monitors, the four more regular fifths had a 20% to 48% lower risk of death from any cause than the least regular fifth, and regularity predicted mortality more strongly than hours slept.8 The NHS puts it plainly: "wake up and get out of bed at the same time every day" and "do not sleep in after a bad night's sleep".10 The gradual shift below is practical guidance drawn from those principles, not a trial result.
| When | What to do |
|---|---|
| Wednesday to Saturday | Move bedtime, wake time and meals 15 minutes later each day, so by Saturday you run an hour later than usual. Skip this if early mornings do not bother you. |
| Saturday night | Bed at your usual clock time; staying up an extra hour hands it to a late night, not to sleep. |
| Sunday | Get up when you wake, even if early by the new clock. Daylight within the first hour or two. No long nap. |
| Monday to Wednesday | Fixed wake time by the new clock, seven days a week. Daylight before midday. Dim lights in the last hour and, as the NHS advises, no tea or coffee for at least 6 hours before bed. |
| The week after | Early waking and 9pm sleepiness should have faded. If poor sleep carries on for months or affects daily life, the NHS says to see a GP. |
How do you help children and shift workers adjust?
Children run on body time more strictly than adults, so the autumn change usually arrives as a week of 5am starts. The same gradual shift works: move bedtime, naps and meals 15 minutes later each day for the four days before, or accept a few early mornings and bring the routine forward together. Sunrise is now an hour earlier by the clock, so a blackout blind keeps the room dark until the new wake time. No trial of children around the clock change was found; this is practical guidance. Night workers on shift when the clocks go back work the 1am to 2am hour twice, so the shift is an hour longer; a fixed anchor sleep after the shift matters more than the extra hour. Older adults, whose clocks already run early, may see a few days of 4am waking instead (why do I wake up at 3am).
Does the autumn clock change make winter tiredness worse?
The change itself is one hour and the body absorbs it within days. What follows is the season: dark evenings from the Sunday and days that keep shortening until late December. The UK Biobank associations above make daylight the lever still in your hands: a walk before midday and a desk near a window.5 The NHS lists light therapy alongside talking therapies and antidepressants as treatments for seasonal affective disorder, and a GP is the route if winter low mood, tiredness and oversleeping persist (when to see a GP about sleep).9
Frequently asked questions
Do you lose sleep when the clocks go back?
Not by the clock: the night of 24 to 25 October 2026 is 25 hours long.1 The tracking study found sleep timing readily adjusted to the autumn change;2 the spring change is the one that shortens sleep.3
Is there a supplement for the clock change?
No supplement has been tested against the clock change, and no ingredient permitted in a Great Britain food supplement carries an authorised claim about sleep or the body clock.12 Melatonin is a medicine here: the NHS says "Melatonin is available on prescription only", mainly for short-term sleep problems in people aged 55 and over;11 the melatonin explainer covers the NHS route. Magnesium contributes to the reduction of tiredness and fatigue and to normal functioning of the nervous system;12 does magnesium help you sleep? sets out its trials, and the sleep supplements evidence page grades the rest.
When do the clocks go forward again, and will that be harder?
At 1am on Sunday 28 March 2027.1 Yes: the 27-study review and the US crash data both point to the spring change as the costly one.3,4 The usual advice is to move bedtime and wake time 15 to 20 minutes earlier for a few nights beforehand and seek morning light that week.
Sources
- GOV.UK. When do the clocks change? gov.uk/when-do-the-clocks-change
- Kantermann T et al. The human circadian clock's seasonal adjustment is disrupted by daylight saving time. Current Biology 2007. PubMed 17964164
- Romigi A et al. The effects of daylight saving time and clock time transitions on sleep and sleepiness: a systematic review. Sleep Medicine Reviews 2025. PubMed 41110263
- Fritz J et al. A chronobiological evaluation of the acute effects of daylight saving time on traffic accident risk. Current Biology 2020. PubMed 32008905
- Burns AC et al. Time spent in outdoor light is associated with mood, sleep, and circadian rhythm-related outcomes: a cross-sectional and longitudinal study in over 400,000 UK Biobank participants. Journal of Affective Disorders 2021. PubMed 34488088
- Crawford MR et al. The British Sleep Society position statement on Daylight Saving Time in the UK. Journal of Sleep Research 2025. PubMed 39439274
- Phillips AJK et al. Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timing. Scientific Reports 2017. PubMed 28607474
- Windred DP et al. Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study. Sleep 2024. PubMed 37738616
- NHS. Seasonal affective disorder (SAD). nhs.uk
- NHS. Insomnia. nhs.uk/conditions/insomnia
- NHS. About melatonin. nhs.uk/medicines/melatonin
- Great Britain nutrition and health claims (NHC) register. gov.uk
