Tonight's sleep starts at breakfast

Most advice about sleep is about the evening. Screens off, no coffee after two, a cool room, read a book. All fair. But we believe the most important decision about tonight's sleep happens at breakfast time, and it is about light.

Your body runs a clock, and the clock is set every morning by bright light reaching the back of the eye. Get outside within an hour of waking, even under cloud, even for ten minutes, and the clock knows what time it is and starts the countdown to the melatonin you will need fifteen or sixteen hours later. Skip it, sit under a bulb and look at a screen instead, and the clock drifts. Then at eleven at night you lie there wondering why you are not tired, and the answer is that morning.

So the rule is light before screens. Out the door before the phone. The dog walk, the school run on foot, coffee in the garden, the bins. Anything that gets daylight into your eyes before a screen does.

It costs nothing, and it is one of the changes people tend to notice first.