2026-08-04 · 5 min read
The real role of screens and light in sleep
Light is the body's strongest time signal, and screens are a source of light. Here is how light and screens shape your sleep and what to actually do about it.
Light is the strongest cue your body uses to tell the time. Bright light in the morning helps anchor your rhythm; bright light late in the evening — especially the blue light of screens — pushes it the wrong way and makes sleep harder.
Get bright light early
The morning is where light helps most. Get a few minutes of daylight soon after waking. It signals daytime and helps your body build sleep pressure for that night.
Dim it late
In the last hour before bed, lower the lights and put the screens down. Dim the room, switch on a warm light, and give your body the cue that night is here.
Add a screen cut-off to your nightly sleep checklist on the sleep checklist page.