When the Clocks Go Back: Sleep Science and the Wisdom of Winter

In the early hours of this Sunday, the clocks go back an hour across Europe. On paper we gain an hour. In the body, something subtler happens: the light arrives earlier in the morning and leaves earlier in the evening, and a few billion internal clocks have to renegotiate their relationship with the sun. When the clocks go back, sleep is where most of us feel it first, and this transition is a perfect invitation to treat sleep as the practice it is.

Why it matters when the clocks go back

Your body runs on a circadian rhythm, an internal cycle of roughly 24 hours that governs sleep pressure, hormone release, body temperature and alertness. This rhythm stays on time mainly through light, especially morning light reaching the eyes. Shift the clock and the light falls at a different social hour, and the body takes days to catch up.

In September 2025, Lara Weed and Jamie Zeitzer of Stanford published a modelling study in PNAS comparing three policies for the United States: permanent standard time, permanent daylight saving time, and switching twice a year. Switching came out worst for what they call circadian burden. Permanent standard time came out best for most people, with the model estimating about 300,000 fewer cases of stroke and 2.6 million fewer people with obesity across the US. Morning types, roughly 15 percent of people, did better under permanent summer time.

The limitations are real and the authors name them: it is a model, assuming tidy sleep habits and ignoring weather and behaviour, and as Zeitzer notes, people's actual light habits are probably much worse than the model assumes. The direction of the evidence still matches the American Academy of Sleep Medicine, which in a 2020 position statement in the Journal of Clinical Sleep Medicine called for permanent standard time as the best match for human circadian biology.

Here in Spain, the government pushed in 2025 to end the twice-yearly change. The EU Council has yet to agree, so this Sunday's change goes ahead, and clocks go forward again on 28 March 2027.

The autumn shift is the gentler one

The good news: the autumn change is generally easier than the spring one. The acute harms highlighted in the sleep medicine statement, such as more traffic accidents and cardiovascular events, are tied mainly to the spring switch, when we lose an hour. In autumn, many people simply enjoy a longer night.

The challenge comes afterwards. Darker evenings arrive an hour earlier, and many of us respond by switching on bright screens and lights. Mornings get light sooner, and that is a gift worth catching.

The Taoist calendar of rest

Long before circadian science, Chinese medicine wrote seasonal instructions for living. The Huangdi Neijing, the Yellow Emperor's Classic of Internal Medicine, devotes a chapter to aligning daily rhythm with the four seasons. For winter, it advises going to bed early and rising late, waiting for the sunlight, keeping the will quiet and storing energy, the way nature itself withdraws into its roots.

I present this as a tradition of practical wisdom, a philosophy of living in rhythm with nature. What I find striking is how closely it resembles modern advice: honour the darkness, let the light set your clock, slow down when the world slows down. The Taoists called it following the Tao of the seasons. Chronobiologists call it entrainment.

A practice for the week of the change

These are simple steps I use myself and give to clients:

1. Catch the morning light. Within an hour of waking, spend ten to twenty minutes outside, even under cloud. This is the strongest signal your clock receives.
2. Dim the evening. After sunset, lower the lights at home and favour warm lamps. Treat the earlier dark as an invitation.
3. Keep wake time steady. If you can, rise at a consistent clock time all week, and let bedtime follow naturally.
4. Use the extra hour well. On Sunday morning, spend it on something restorative: a slow walk, a long breakfast, a nap later if you need it.
5. A five-minute descent. In bed, breathe out longer than you breathe in for ten breaths. Then imagine each part of the body growing heavy and warm, from feet to crown, while silently counting down from fifty. If your mind wanders, simply start the count again.

That last exercise is a basic form of self-hypnosis, and it works well because it occupies the narrative mind gently while the body does what it already knows how to do.

Winter as a practice

Every year our culture fights the dark: more light, more caffeine, more year-end deadlines. The older traditions and the newer science seem to agree on a softer approach. Let winter be a season of depth. Sleep a little longer if your life allows it. Spend evenings in lower light, in conversation, in stillness. Treat the turning of the clocks as a small ritual marking a change of inner season.

For guided sleep and relaxation recordings to support the transition, explore the Hypnosis Library.

Related reading

• What Is Hypnagogia? The Creative Trance at the Edge of Sleep
• Self-Hypnosis for Stress: What Two New Studies Reveal
• Hypnosis for Chronic Pain: What a New Neurology Trial Shows

Sources

• Weed, L., & Zeitzer, J. M. (2025). Modelling study of time policy and circadian health. Proceedings of the National Academy of Sciences, published 15 September 2025 (title paraphrased). Stanford Medicine news
• Rishi, M. A., et al. (2020). Daylight saving time: an American Academy of Sleep Medicine position statement. Journal of Clinical Sleep Medicine. Report
• Euro Weekly News (2026, September 5). Spain's 2026 plan to end clock changes has failed, and the next change is already locked in
• Barcelona City Council, Time Use (2025). Growing scientific evidence on the negative effects of time change
• Huangdi Neijing Suwen, chapter 2, on regulating the spirit according to the four seasons.