It’s 7 o’clock, the alarm rings at its usual time, but the body howls that it’s still the middle of the night. Three weeks after the switch to winter time on October 25, 2026, millions of French people are still dragging this diffuse fatigue, this mood that swings on a daily basis, which should no longer be a concern. A simple one-hour shift, almost trivial on paper, but which continues to silently cause damage. Why does the body take so long to digest this change, and above all, how can we help it finally move on?
- The circadian clock resets with light, not instantly, which explains an adaptation that can take several weeks after the time change.
- This shift weakens sleep, mood, and vigilance, with an increased risk of late-afternoon road accidents.
- Advancing bedtime by 15 minutes per day and exposing oneself to natural light upon waking helps the body resynchronize more easily.
- Why your internal clock still rejects this one-hour shift
- Sleep, mood, vigilance: the triple shock your body endures
- The gentle strategy to help your body finally move on
Why your internal clock still rejects this one-hour shift
The transition to winter time, which occurred in the night from October 24 to October 25, 2026, offered sixty extra minutes of sleep—a rare 25-hour night where clocks moved back from 3 a.m. to 2 a.m. It may seem like a gift, but it is not truly so for the circadian clock, that internal mechanism that synchronizes body temperature, hormones, and sleep cycles. Unlike a watch, this biological clock does not reset with a snap of the fingers. It reacts mainly to light, and this change abruptly shifts the light cues of morning and evening. As a result, the body continues to operate on its old rhythm for several days, or even weeks for the most sensitive individuals.
Sleep, mood, vigilance: the triple shock your body endures
This shift, however small, does not stop at a few extra yawns in the morning. It affects multiple fronts at once. Sleep becomes more fragmented, less restorative, because the morning light—the main signal indicating that it is time to wake up—arrives later. Mood also suffers, with a gradual dip in energy, particularly as days shorten. Finally, vigilance declines, and this is no minor detail: rain, fallen leaves, and reduced light create a delicate cocktail on autumn roads, making pedestrians and cyclists much harder to spot in the late afternoon. Some studies even point to a link between this circadian disruption and higher risks of diabetes, obesity, cardiovascular problems, not to mention the rise in fatigue-related accidents.
What is striking is how quickly daily habits are thrown off balance. Outdoor terraces empty earlier, after-school activities drift toward gloom, and, without anyone really noticing, the entire rhythm of the day contracts.
The gentle strategy to help your body finally move on
Good news: there are simple levers to support this transition rather than endure it. The most recommended approach is to progressively shift your bedtime, about 15 minutes earlier each day in the days around the change. This technique mirrors what pediatricians use to recalibrate children’s sleep, and it works just as well for adults. Exposure to natural light also plays a key role: opening the blinds as soon as you wake up, or better yet, going for a short daylight walk, helps the brain understand that it’s time to get moving. Here are a few simple habits to adopt to limit the effects of this shift:
- Shift bedtime by 15 minutes per day before the change
- Expose yourself to natural light as soon as you wake up
- Avoid bright screens late in the evening
- Keep regular meal times
- Prefer light physical activity during the day
That famous extra hour of sleep can, in fact, reduce part of the accumulated sleep debt and lift spirits, provided the body is given time to readjust. Three weeks, in the end, isn’t that long to restore a balance that light itself sometimes takes longer to relearn.
