How dark should a bedroom be for sleep?
As dark as you can make it. In 2022, an international group of 18 researchers recommended that the place you sleep should be as dark as possible, with a little dim light if you need to see at night1. Curtains that close properly and a covered standby light might help.
What the research found
The same group looked at the whole day, not only the night. They recommend bright light by day, daylight first, and much less in the hours before bed1. These are expert recommendations, not the result of a single trial1.
Screens are worth a thought as part of your routine. In a small lab study, people reading on a lit-up tablet in the hours before bed took longer to settle than when they read a printed book, and felt less alert the next morning2.
See the details
The figures use a special scale called melanopic EDI, taken at the eye, which estimates how much a light reaches your body clock1. An ordinary light meter or phone app doesn't show it.
| When | Recommended |
|---|---|
| By day | At least 250 lux melanopic EDI |
| From 3 hours before bed | At most 10 lux |
| While sleeping | At most 1 lux |
| If you need to see at night | At most 10 lux |
Worth a try
- Outside lights. A streetlight or security light might be finding its way round the curtains.
- Standby lights. A bit of tape over a charger or TV light is quick to try.
- A book for the last half hour. Instead of the phone, if you feel like it.
- Time outside by day. Ten minutes in the morning is an easy start.
These are everyday suggestions based on the recommendations above, not findings from a study of each one.
Curious about your own room?
Dormio sits by the bed and keeps an eye on the room: fresh air, warmth, humidity, light and sound. It looks at the room, not at you.