Sleep · Protocol 2 of 15
Step out into late-afternoon light
1In 30 seconds
Go outside for at least 10 to 15 minutes in the late afternoon or early evening, before the sun sets. This balances your morning light and makes the lights and screens you see later at night less able to disturb your sleep.
2Picture it
3Why do it
- 1
It helps keep your sleep and wake times steady, because evening light gently balances the push from morning light.
- 2
It partly protects you from the sleep-wrecking effect of bright lights and screens after dark.
- 3
It is a pleasant break that gets you away from your desk and into fresh air.
4How to do it
- In the late afternoon or early evening, go outside and stay there for at least 10 to 15 minutes before the sun goes down.
- If you can, face or walk towards the west, where the sun is setting. You do not need to watch it touch the horizon.
- As in the morning, skip the window, the sunglasses and the brimmed hat for this short spell.
- For a clearer view of the sky, try a rooftop or walk a few blocks away from tall buildings.
- Make a special effort on overcast days, when you are likely to have spent more time indoors.
- If you cannot get out near sunset, any outdoor stroll in the afternoon still helps.
5Make it work in India
- Across most of India the sun sets between about 5:30 and 7 p.m., so a short walk at the end of the office day or a tea break on the terrace fits well.
- In north Indian summers, late afternoon can still be very hot. Choose a shaded spot, carry water and go out closer to sunset.
- An evening walk in the local park or around the colony before dinner, perhaps with family, does the job nicely.
6The long read: the science1 min read · tap to open
Your master clock, the SCN, is not one simple timer. It contains two linked rhythms that run slightly out of step, rather like singers in a round. One tends to lock on to sunrise and the other to sunset. They keep checking on each other so that neither runs too fast or too slow.
This matters because light at different times nudges your clock in different directions. Morning light pulls your clock earlier, so you get sleepy and wake earlier. Late-day light pushes it later. Getting both is like having bookends on a shelf. Each one holds the other in place, so your sleep times stay steady through the seasons.
There is a second benefit. After dark, the light-sensing cells in your eyes become more and more sensitive with every passing hour. Even a few seconds of bright light at night can shift your clock, and your eyes add up all the light from lamps and screens. Viewing daylight in the afternoon seems to turn down that sensitivity a little, so the lights you meet later in the evening do less damage to your melatonin.
This effect is strongest if you spend most of your day under indoor lights. Then the contrast between your dull day and your bright evening is at its worst. Think of afternoon light as a partial vaccine against evening screens. It does not replace dimming the lights at night, but it softens the blow.
Early evidence Some human research suggests daytime light makes evening lamps and screens less disruptive, but the specific benefit of viewing late-afternoon sun has not been well tested.
Questions people ask
I work until after dark. What can I do?
Step outside at any point in the afternoon, even for a few minutes on a balcony or a quick walk round the block. Any ambient daylight before dark is better than none.
Do I need to see the actual sunset?
No. Seeing the sun go down is a lovely bonus, but general outdoor light in the late afternoon is what counts.
7Be careful
Do not look straight at the sun, even when it is low. In hot weather, protect yourself from heat and dehydration, especially if you are older or have a heart condition.
8Try it for 7 days
Tap a day each time you got late-afternoon light.
From the book: “View Sunlight in the Late Afternoon” (Sleep Protocol 2). Evidence rating and India notes are our own.