How to get a genuinely dark bedroom

Light gets into a bedroom in four places, and the fabric is the last of them. In order of how much difference each one makes: the gap down each side of an inside-mounted shade, the open top above the roll, the join where two treatments meet or where a panel does not return to the wall, and finally the cloth itself. Fix them in that order. An outside mount with a generous overlap, a cassette or cornice closing the head, and side channels where the room faces the sun will do more for a dark bedroom than any upgrade to the fabric.

The four places, in order

1. The sides

A roller shade mounted inside the opening is cut narrower than the opening so it can roll freely. That clearance is permanent, designed, and at exactly the height of your head on the pillow. It is almost always the biggest single source of light in a bedroom.

Fix: mount outside the opening with a generous overlap onto the wall on each side, or add side channels. An outside mount reads larger and covers some of the casing — that is the trade, and in most bedrooms it is worth it.

2. The top

An open roll has nothing above the fabric. Light comes over the tube and down the wall, and on an east-facing bedroom it is what wakes you before the alarm.

Fix: a cassette or a built cornice over the roll. A fascia helps; a cassette or a cornice closes it. The four headers compared.

3. The joins

Where two panels of drapery meet in the middle, and where a panel ends without returning to the wall, are both open seams. A generous overlap at the centre and a proper return that wraps the panel back to the wall close them.

4. The cloth

Only now does the fabric matter. And for most bedrooms room-darkening is enough — it takes out the streetlight and the early sun and leaves a soft edge glow that most people sleep straight through. Go to blackout when someone sleeps in the daytime, when it is a nursery, or when the room doubles as a media room. Room-darkening vs blackout.

Where drapery fits in the sequence

Blackout-lined drapery is a genuinely good answer and it brings two things a shade cannot: it absorbs sound, and it cuts the cold draught that comes off a large pane of glass in a Northeast Ohio February. It also has the same weakness as a shade, in the same places. Light comes around the sides where the panel ends, and over the top where the rod is.

Which is why a return — the part of the panel that wraps back to the wall at the outer edge — matters more than anything else on the order. A drapery panel with a proper return and a generous centre overlap is a dark room. The same panel on a plain rod with the ends open is a nicely dressed one. Lined and blackout drapery.

The things that are not the window

Worth saying, because people spend money on the window and then lie awake anyway. A standby LED on a television is genuinely bright in a dark room. So is a smoke-alarm indicator, a phone charging on a nightstand, and the strip of light under a door onto a lit landing. In a room you have properly darkened, those become the brightest things in it.

The dual-roller answer

If the bedroom also has a daytime job — and most do — a dual roller gives you a light-filtering or solar fabric for the daytime and a full blackout drop behind it for the night, on one bracket with one header. It is the neatest solution to a bedroom that is also a room. Dual day-night shades.

Layering with drapery

Blackout-lined drapery over a room-darkening shade is the other route, and it brings the acoustic and draught benefits with it. The light that remains comes around the sides and over the top, exactly as with a shade — so the return and the overlap are what decide the result. Lined and blackout drapery.

Have a designer look at the room