Autumn makes you tired mainly because the UK loses daylight faster in late September and October than at any other time of year, so your body clock gets a weaker morning signal, melatonin lingers later into the morning and you spend more of the day indoors. In London, daylight falls from 12 hours 39 minutes on 15 September to 8 hours 52 minutes on 15 November, and the clocks go back on 25 October. Most autumn tiredness is this, and it is adjustable; tiredness that does not lift is worth a GP visit.
At DAYARC, a new UK circadian rhythm startup, we make two bright-light lamps for the morning, so the September-to-November slide is the part of the year we think about most.
Why does autumn make me tired, even after a full night's sleep?
Your circadian rhythm is the roughly 24-hour body clock that decides when you feel sleepy and alert. It is set each day by light reaching the eyes: specialised cells in the retina signal the brain's master clock, and a bright morning tells it the day has started. Light and your daily rhythm explains the mechanism.
Melatonin is the hormone that signals darkness to the body. It rises in the evening and falls in the morning, and morning light suppresses it. When you wake in the dark, as more of the UK does from October onwards, that fall comes later, the clock drifts later day by day, and the alarm lands earlier in your biological night. The result is the heavy, slow waking people describe as autumn tiredness, even after eight hours in bed.
How fast does the UK lose daylight in autumn?
Faster than at any other time. The Met Office describes the autumn equinox, around 22 September, as the point of nearly equal day and night, and the days shorten fastest around it: in London, about 3–4 minutes of daylight are lost every day through October. By the solstice on 21 December the loss has slowed almost to nothing, but the day is already short.
| Month (15th) | London sunrise–sunset | London daylight | Edinburgh sunrise–sunset | Edinburgh daylight | What changes |
|---|---|---|---|---|---|
| September 2026 | 06:35–19:14 | 12 h 39 min | 06:44–19:30 | 12 h 46 min | Most alarms still ring after sunrise |
| October 2026 | 07:24–18:07 | 10 h 42 min | 07:44–18:11 | 10 h 28 min | Sunrise after 07:00 in London from about 1 October; fastest loss of the year |
| November 2026 | 07:18–16:10 | 8 h 52 min | 07:49–16:04 | 8 h 15 min | Clocks went back on 25 October; sunset before 16:30 in London from 3 November |
| December 2026 | 08:00–15:51 | 7 h 51 min | 08:38–15:37 | 6 h 59 min | Shortest day 21 December; latest sunrises after Christmas |
Between 15 September and 15 November London's sunrise moves from 06:35 to 07:18 even though the clocks went back in between, and Edinburgh's from 06:44 to 07:49. Sunrise passes 07:30 in London from about 19 October and 08:00 in Edinburgh from 23 October. A 6.30am alarm that rang in daylight in August rings in the dark by mid-October.
What does the clock change do to you?
The clocks go back one hour at 2am on Sunday 25 October 2026, as GOV.UK confirms, when British Summer Time (GMT plus one hour, used from late March to late October) ends and the UK returns to Greenwich Mean Time. Sunrise in London moves from 07:40 on 24 October to 06:41 on 25 October, so mornings get lighter for a few weeks. Sunset moves from 17:48 to 16:46, and afternoons go dark at a stroke.
Two things follow. The lighter mornings fade quickly, with London sunrise back at 07:18 by 15 November and 07:44 by 1 December. And the dark afternoons cut into outdoor time, because a walk home at 5pm is now a walk in the dark. Our guide to the October clock change covers how to shift sleep and mornings around it.
What else changes in autumn?
- Less time outdoors. Colder, wetter weather and dark evenings mean fewer walks and more hours under indoor light, which is about 300–500 lux in a bright office against 1,000–5,000 lux outdoors on an overcast day.
- The return to routine. September brings new terms, new timetables and earlier alarms, and a body clock that drifted late in August has to be dragged back.
- Heating and less movement. Warm, closed rooms leave many people drowsier by mid-afternoon, and less activity feeds into poorer sleep.
- Vitamin D. The NHS says that between October and early March we do not make enough vitamin D from sunlight in the UK, and that adults should consider a daily 10 microgram supplement in autumn and winter. That is separate from light through the eyes; a bright-light lamp does nothing for it.
Could it be more than tiredness?
For some people the autumn slide is the start of something heavier. Seasonal affective disorder (SAD) is a form of depression that comes and goes in a seasonal pattern, usually worse in winter. The NHS lists its symptoms as persistent low mood, a loss of interest in things you usually enjoy, feeling irritable or worthless, difficulty concentrating, eating more and sleeping more, and says to see a GP if you think you might have it. Winter blues or SAD walks through the difference.
Tiredness on its own has many other causes, including low iron, thyroid problems, sleep apnoea and depression, none of which follow the sunrise. If you have felt tired for weeks regardless of the weather, see your GP.
What helps with autumn tiredness?
The NHS lifestyle advice for SAD is a sensible list for anyone who feels the season: get as much natural daylight as you can, exercise regularly, keep in touch with people, keep up your usual activities, keep a regular sleep pattern, and avoid excessive alcohol and devices before bed. For autumn mornings:
- Get light soon after waking. Open the curtains, eat breakfast by the window, and once sunrise slips past your alarm, consider a bright-light lamp at the table for 20–30 minutes. DAYARC Rise is manufacturer-rated at 10,000 lux at approximately 30–36 cm, DAYARC Mini at 10,000 lux at approximately 25 cm; both are UV-free and run from the mains. Our month-by-month guide suggests when to start.
- Keep the same wake time every day, including weekends. A lie-in on Saturday and Sunday shifts the body clock later and makes Monday's dark alarm worse.
- Get outside at lunchtime. By November it may be the only daylight you see on a working day.
- Dim the evenings. Bright light late in the day pushes the clock later; lower lamps and screens in the last hour before bed help the next morning.
- Keep moving. A short walk, ideally outside in daylight, is one of the quickest ways through the morning fog.
The NHS says bright light therapy is not usually available on the NHS because there is not enough evidence to tell whether it is effective, though many people find it helps their symptoms. A morning lamp is one habit on the list, not the whole answer; why winter mornings feel so tiring goes deeper.
Frequently asked questions
Is it normal to feel more tired in autumn?
Yes. Darker mornings give the body clock a weaker signal, days shorten by 3–4 minutes a day in October, and most people spend more time indoors. It usually eases with a steady wake time and morning light.
Why am I so sleepy when the clocks go back?
Your body clock does not move an hour overnight, so meals, alarms and bedtime land an hour off for a few days after 25 October. Hold a regular wake time and use the lighter mornings while they last.
Does less daylight make you tired in the UK?
It can. Between 15 September and 15 November London loses nearly four hours of daylight and Edinburgh more than four and a half, and light through the eyes is the main thing that sets the body clock.
When should I see a GP about tiredness?
If tiredness has lasted for weeks regardless of sleep, daylight and routine, comes with persistent low mood or loss of interest, or is affecting daily life. Persistent tiredness has many causes, and a GP can check the common ones.
Where does this leave you?
Autumn tiredness is mostly a light problem with a routine answer: the same wake time, daylight as soon as it is there, and a bright-light lamp for the mornings when it is not. If that lamp will sit at the same table every day, DAYARC Rise (£199) is built for it; if it needs to fold away, DAYARC Mini (£49.99) is the compact option. Our comparison page sets them side by side.
About DAYARC
DAYARC is a new UK circadian rhythm startup. We make two bright-light lamps for the morning: DAYARC Rise (£199), a full-size lamp rated at 10,000 lux at approximately 30–36 cm, with four brightness settings, a 15 to 60-minute timer and adjustable height and angle; and DAYARC Mini (£49.99), a compact lamp rated at 10,000 lux at approximately 25 cm, with a folding stand that doubles as its cover. Both use UV-free LEDs and run from the mains. We publish plain specifications with the measuring distance, we do not make medical claims, and we write the DAYARC Journal to help people build a simple morning light routine around their own daily rhythm. Both lamps are in stock in the UK and dispatched within 2 working days. You can read more about how we think on our approach page or compare the two lamps.
This article is general information, not medical advice. Check with a GP or qualified healthcare professional before using bright light if you have an eye condition, a condition affected by bright light such as bipolar disorder, or take medicines that increase your sensitivity to light. If you have persistent low mood or think you may have depression, speak to your GP. If you need urgent help, contact NHS 111, or call 999 in an emergency. Samaritans are available on 116 123, free, day or night.