At 2am on Sunday 25 October, the clocks go back an hour. For a week or so it feels like a gift. Then you notice you’re driving home in the dark, and by December it’s dark before half past four.

If you start early, finish late or spend the day under strip lights, you can go most of the winter without seeing proper daylight on a working day. That matters more than it sounds. And the fix is simpler than most winter advice.

 

Your body clock runs on light

Indoors, even a well-lit office is dim compared with outside. Researchers put ordinary daylight at around fifty times brighter than standard office lighting, and direct sun at two hundred times. Your eyes adjust, so you barely notice. Your body clock does notice.

Light in the morning nudges that clock earlier, so you feel sleepy at a sensible time and wake more easily. Light late in the evening pushes it the other way. In one winter study of students in Seattle, each hour of daylight moved their body clocks about half an hour earlier. That held even on grey, overcast days.

 

It may matter for mood too

Researchers led by Sean Cain in Melbourne looked at 86,772 people in the UK who wore light sensors on their wrists. Their average age was 62. People who got more daylight had a lower risk of depression. People who got more bright light at night had a higher one.

The study shows a link, not proof that light is the cause. But it points the same way as everything above. As Cain put it, “It’s about getting bright light in the day and darkness at night.”

 

The one change worth making

When the clocks go back, the mornings suddenly get lighter. For a few weeks, it’s light by the time most people are up. By December that’s gone again, so use it while it’s there.

Try this: get outside within an hour of waking, for as long as you can manage. Walk part of the way in. Park at the far end of the car park. Take your first cup of tea to the back door. Grey sky counts.

If mornings are impossible, a lunchtime walk is the next best thing. Then do the opposite in the evening: lamps rather than the big light, and the phone put away for the last stretch before bed.

 

When it’s more than tiredness

For some people, winter brings more than a slump: low mood that won’t lift, losing interest in things, sleeping much more than usual. That can be seasonal affective disorder. The NHS recommends getting as much natural daylight as you can, and seeing a GP if you think you might have it. It’s common, and it’s worth mentioning.