How To Set Up a Bedroom for Actual Darkness

September 21, 2026
By Sleeping Express

Set up a bedroom deserves a clear, practical explanation. Bedroom darkness deserves a clear, practical explanation. People buy blackout curtains, hang them, and find the room is still annoyingly light. That is because a curtain deals with one of about six light sources in a typical bedroom, and rarely the brightest one.

The short answer. Light leaks around blinds, not through them. Deal with the edges first, then the standby LEDs, then the light under the door. A sleep mask solves all of it for under a tenner if you can tolerate wearing one, and it is worth testing that before spending on window treatments.

Set up a bedroom: Bedroom darkness: Find out how dark it needs to be

Before buying anything, test the premise. Wear a decent sleep mask for a week. If your sleep improves noticeably, darkness is worth investing in for your room. If it makes no difference, the problem is something else and blackout blinds will be an expensive disappointment. This one test saves a lot of people a lot of money.

Where the light actually comes from

Source	How much it matters	Fix
Gaps at the sides of a blind	The biggest single leak	Wall-mounted blackout with side channels, or a curtain overlapping the frame
Gap at the top of a curtain	Large	Pelmet, or ceiling-mounted track
Standby LEDs	Small but disproportionately annoying	Blackout stickers, or turn devices off
Light under the door	Moderate in a shared home	Draught excluder
Streetlight through thin curtains	Moderate	Blackout lining behind existing curtains
Phone screen	The one you control	Charge it in another room

The side gaps are where nearly every blackout blind installation fails.

Why blinds leak and curtains do not

A roller blind fitted inside the window recess has a few millimetres of clearance on each side so it can roll. Light enters through those gaps and, because the wall around them is dark, reads as two bright vertical strips. Fitting the blind outside the recess, overlapping the frame by at least 10cm each side, removes the problem entirely. Blackout side channels do the same job more neatly and cost more.

Curtains are more forgiving because they overlap in the middle and hang past the frame, but they have their own leak: the gap at the top, where light passes over the rail. A pelmet or a ceiling-mounted track fixes it.

The small light sources

Router, TV, extension leads and smart plugs all have LEDs. A pack of blackout stickers deals with them all in ten minutes.
Digital alarm clocks are bright and they invite clock-watching. Turn the display away from the bed or use one that dims.
Charge your phone outside the bedroom. This does more for sleep than any amount of blackout, for reasons that are only partly about light.
A smoke alarm LED cannot be covered. Live with it or move the bed.

Do not overdo it

Complete darkness through the night is good. Complete darkness in the morning is not, because morning light is the strongest signal your body clock has for setting itself. If you blackout a room perfectly and then wake by alarm in the dark, you can end up feeling worse rather than better. A gradual sunrise lamp, or a blind you open on waking, restores the signal.

When it is noise, not light

Plenty of people blame light for waking them when the actual cause is a neighbour, traffic or a partner. Bedphones from DubsLabs are flat enough to sleep on your side in, which is the problem with ordinary headphones in bed.

See sleep headphones

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Set up a bedroom: darkness checklist

Set up a bedroom by checking light at the window edges, doors, electronics, and every other source you can see after your eyes adjust.