Home theater lighting

Every other page on this site is about getting enough light into a space. This one is about the opposite - and it is the only room where the honest answer involves subtraction.

But not to zero. The instinct is that a home theater should be as dark as possible, and that turns out to be wrong for a specific, physiological reason.

A bright screen in a black room presents your eye with an enormous brightness ratio. Your pupils cannot settle: they contract for the picture and dilate for the dark surroundings, continuously, for two hours. That is what produces the tired, strained feeling after a long film in a dark room - and it is fixable with a very small amount of light in the right place. The underlying mechanism is the same one described in glare and visual comfort.

Bias lighting is a strip behind the screen, aimed at the wall rather than at you, so the area immediately around the picture is gently lit. It does two things: it reduces the contrast ratio your eye has to cope with, and it gives your eye a white reference that makes on-screen blacks read as deeper rather than as gray.

Three rules make the difference between bias lighting and a decorative glow.

• Neutral white, around 6500K. That is the reference white most video is mastered against, so it does not shift your perception of on-screen colors. Colored bias lighting looks dramatic and works against the picture.
• Dim. A fraction of the screen's own output. If you notice the light rather than noticing that the wall is softly visible, turn it down.
• Hidden. The strip must not be directly visible from the seating position - it goes behind the panel, facing the wall.

The LIFX Z TV is built specifically for this application and publishes 1,500 lumens, which sounds like far too much and is the point - you run it at a small fraction of that, and having headroom means the low settings stay clean. The Govee M1 is the alternative, with dedicated warm and cool white LEDs so its white is a real white rather than a mix of red, green and blue. Both are covered in best smart light strips.

A plain COB strip at CRI 90+ is the option for anyone who wants the effect without an app - it is fixed white, which for this job is not a limitation.

The second problem in a room built around a screen is that people leave it mid-film - and the available options are usually to walk out in the dark or to switch on a room light and ruin everyone's dark adaptation.

Cinemas solved this with aisle lighting: very low level light at floor height, along the route, aimed downward. The same approach works at home. A dim strip along the base of a step, under a seat plinth, or along the edge of the walking route gives you enough to move safely and stays entirely out of the sight line to the screen. It overlaps directly with stair and landing lighting, where the same under-nosing approach appears for the same reason.

Keep this layer warm rather than neutral - it is doing the opposite job from the bias light, and warm light at very low levels preserves dark adaptation better.

For the room's normal lighting when nothing is playing, tunable bulbs in the ordinary fittings let one set of lamps be a normal living room in the afternoon and disappear at showtime. A scene that drops the room lights, brings up the bias strip and leaves the path light on is exactly the kind of automation that survives - unlike most of them, per schedules and automations.