Light · Protocol 2 of 5
Catch late sun to shield your night
1In 30 seconds
Some time after midday and before sunset, step out and look towards the sun’s side of the sky for 5 to 30 minutes. This seems to make your body less sensitive to the indoor lights and screens you meet later. Use real sunlight for this, not a bright lamp.
2Picture it
3Why do it
- 1
Bright daylight earlier on seems to blunt how much evening lights and screens cut your melatonin, the hormone that eases you into sleep.
- 2
The warm, reddish light of a low sun is a natural signal that night is coming, which helps keep your body clock on time.
- 3
A short break outside in the late afternoon also lifts your energy at the time of day when many people slump.
4How to do it
- Pick a time after the sun has passed its highest point and before it sets; the exact clock time is up to you.
- Go outside for 5 to 30 minutes and face the direction of the setting sun.
- Remove sunglasses and any brimmed hat, though your normal glasses or contact lenses are fine.
- Blink as often as you like and look near the sun, never straight into it.
- Do not swap this for a 10,000 lux lamp in the evening, because its strong, blue-rich light can push your sleep later.
- Spend plenty of the rest of your day in bright light too, since more daytime light seems to give more protection at night.
5Make it work in India
- In Indian summers the 4 p.m. sun is still fierce, so wait for the last hour before sunset, or sit in light shade facing the western sky.
- A walk to the sabzi market, a game of gully cricket with the children or chai on the terrace around sunset all count.
- Stuck in an office or hospital all day? Step out to the car park or gate for five minutes before you head home, with your phone in your pocket.
6The long read: the science2 min read · tap to open
Melatonin and cortisol work like a seesaw. When one is high, the other is low. Melatonin begins to creep up in the late afternoon, climbs sharply in the hour before your natural bedtime and stays high through the night.
Bright light is the main thing that pushes melatonin down. Light rich in short wavelengths, such as blue-white LEDs and screens, is especially strong at this. Less than 30 seconds of bright LED light on your eyes at night can cut melatonin noticeably. That is why switching on a bathroom light at midnight can leave you wide awake.
Here is the interesting twist. Small studies show that bright light earlier in the day makes you less sensitive to light later. In one, people who got up to five hours of bright light a day for a week lost less melatonin under night light than after a week spent in dim light. In another, women who saw bright light in the early evening had a smaller melatonin drop when they met light later at night.
The low evening sun also has a different colour. Near the horizon, the air filters out much of the blue and ultraviolet, so the light looks orange or red. These long wavelengths hint to your brain that night is near. A 10,000 lux lamp sends the opposite message, which is why it is a morning tool only. Teenagers seem to get less of this protective effect, so dark nights matter even more for them.
Early evidence A few small studies suggest daytime and early evening bright light softens the melatonin drop caused by light at night, but larger trials are still needed.
Questions people ask
What if I can only get out at lunchtime?
Midday light still adds to your daytime dose, which seems to protect you at night. Add a few minutes near sunset whenever you can, even a short pause outside before you leave work.
Does this mean I can use screens late at night?
No. Afternoon light softens the effect of night light but does not cancel it. Dimming your lights later on still matters a great deal.
Can I watch the sunset through a window?
It is better than nothing, but glass filters out a lot of useful light. Step outside or open the window if you can.
7Be careful
Never look directly at the sun, even when it is low and orange. In hot months, carry water and go back indoors if you feel dizzy or overheated.
8Try it for 7 days
Tap a day each time you saw afternoon sun.
From the book: “View Sunlight in the Late Afternoon and/or Early Evening to Help Buffer Against Negative Effects of Artificial Light at Night” (Light Protocol 2). Evidence rating and India notes are our own.