How Dim Should the Lights Be in the Hours Before Bed?

Aim for 10 lux of melanopic EDI at your eyes from at least three hours before bed, then under 1 lux once the room is for sleeping. That is what "dim the lights" should actually mean, and it is the number the advice almost never gives you. It comes from a consensus recommendation published in PLOS Biology, and it is read facing the room at eye height rather than off the tabletop.

Melanopic lux is not the number a light meter shows, which is where this gets misread. A warm-white LED at 2700K to 3000K has a melanopic ratio below 0.35, so a meter can read close to 29 lux in front of your face and the melanopic figure still lands under the cap. A cool white 6500K lamp, at 0.83, runs out at about 12. The Houseland backlit plaster ring hides a warm-white LED strip with remote dimming and several modes, which is the shape of evening layer this asks for: warm, low, and adjustable from the sofa.

How dim should the lights be before bed, exactly?

Three numbers cover a whole day: at least 250 lux melanopic EDI in daytime, 10 lux maximum in the evening, 1 lux maximum while you sleep. Every one of them is read at the eye in the vertical plane, roughly 47 in (1.2 m) off the floor, which is about where a face sits in an armchair.

The start time is the half that gets dropped. Three hours before an 11pm bedtime is 8pm, so the dimming belongs to the middle of your evening, not to the last five minutes of it before the pillow. The night-time allowance is real too: those same recommendations put 10 lux on a task that needs vision, so nobody has to cross a landing at 3am in the dark and count the stairs.

What does 10 lux actually look like in a room?

About a fifth of an ordinary living room, and about three times the last of the dusk. Wikipedia's illuminance table gives 50 lux for family living room lighting, 80 lux for an office hallway, 320 to 500 lux for office lighting, and 3.4 lux for the dark limit of civil twilight. A full moon sits between 0.05 and 0.3 lux, so the target is a long way from darkness.

Those are photopic lux, the meter kind, but they set the scale. Multiply a 50 lux living room by the 0.35 factor of a warm bulb and it lands near 17 melanopic lux, over the cap before a second lamp gets switched on. Run the same room on cool white lamps and it reads about 42. Most rooms are not marginally over. They are two to four times over.

What that costs has been measured rather than guessed. In a laboratory study of 116 adults published in the Journal of Clinical Endocrinology and Metabolism, an evening under ordinary room light of less than 200 lux, which worked out at 60 to 130 lux at the eyes, cut melatonin by 71.4% and shortened the nightly melatonin window by around 90 minutes against an evening spent under 3 lux. Nobody sitting in that room would have described the lighting as bright.

Warm white vs cool white: which bulb buys more light?

Warm white buys you more than double the meter reading for the same melanopic dose. The conversion factor is the melanopic daylight efficacy ratio, daylight set at 1.0: a 2700K to 3000K LED comes in under 0.35, while a 6500K cool white one sits at 0.83.

The Illuminating Engineering Society makes the same point from the other end: swapping a 6500K cool white source for a 3000K warm white one cuts melanopic EDI by more than half while the photopic illuminance stays exactly where it was. That is why the colour of the bulb is worth more to you than its wattage after dark. The melanopsin cells carrying this signal peak near 480 nm, deep in the blue, and a warm source has less to give there.

So two lamps that look equally bright can differ by a factor of two or three in what they do to your evening, and swapping the bulb colour costs a few dollars.

How do I measure the light at my own eye?

Hold the sensor where your head is, pointed at the room, and take a reading in every seat you use after dark. The recommendation specifies the vertical plane at eye height for a reason: light arriving at your face is the only light this rule is about.

1. Sensor at 47 in (1.2 m), facing out. Sit down first, then hold the phone or meter beside your temple with the sensor pointing where you are looking. Laid flat on the coffee table it is measuring the table.
2. One reading per seat. Sofa, armchair, desk, the edge of the bed. A room is rarely a single number, and the seat directly under a ceiling fitting can read several times the seat in the corner.
3. Convert with the ratio for your bulb. Multiply the meter figure by 0.35 for warm white LED, 0.83 for cool white, 1.0 if daylight is still coming in. Compare the result with 10, not the raw reading.
4. Count every screen as part of the room. Read it again with the television running and the phone in your hand. Both are light sources aimed at your face, and both belong in the total.
5. Then judge it against your own sleep. The same paper reports more than tenfold variation between individuals in how strongly light suppresses melatonin, so 10 lux is a population figure and yours may be gentler or harsher.

With no meter at all, borrow a reference you already know. Wait for the last of the dusk outside, the 3.4 lux mark, and set the room to sit somewhat above that rather than far above it. Expect it to feel too dim for the first few evenings, because your eyes are adapted to a 300 lux room. For the one task that really does need more, a reading light on an adjustable arm puts light on the page instead of into the room.

What should replace the ceiling light in the evening?

One warm, dimmable source down at wall height, throwing its light at a surface rather than into your eyes. A ceiling fitting is the worst instrument for this job: it sits high in your field of view, it lights the entire room at one level, and unless it is on a dimmer it offers you 300 lux or nothing.

Wall washing works because the cap is on light arriving at the eye. Light that leaves a hidden strip, lands on plaster and comes back to you has given up a good deal on the way, so the room reads as lit while the figure at your face stays low. You still have to measure it. Nobody publishes a melanopic EDI for a decorative fitting, ours included, and a description that says "soft glow" is not a number you can check.

The Houseland plaster ring is built to that shape: the warm-white LED strip is hidden behind the piece so the light lands on the wall, the remote covers brightness and several modes without anyone getting up, and it hangs on two screws with no wiring to run. If you are weighing it against a bare strip taped behind furniture, a backlit panel and an LED strip behave differently in a bedroom. If the wall you want has no socket near it, battery and plug-in versions land in different places on brightness and on cable.

From the shop

Backlit Plaster Wall Art, Japandi LED Ring with Walnut Shelf and Bud Vase

Hand-applied sand plaster over a laser-cut MDF base, with a hidden warm-white LED strip and a remote for brightness and modes. 47 in (120 cm) across including the shelf overhang, 27.6 in (70 cm) tall, wall mounted on two screws.

View the backlit plaster ring — plug-in or battery options & current price

Does the screen in your hand undo the rest of it?

It can, easily: modern displays are capable of delivering more than 60 lux of melanopic EDI at the eye, six times the entire evening allowance. The PLOS Biology authors cite that figure alongside evidence that display light is enough on its own to blunt the evening melatonin rise and cut sleepiness.

The arithmetic is unforgiving. A phone at reading distance fills a large slice of your field of view with an emitting surface, so it is not competing with the room lighting, it is the room lighting. Taking the room down to 10 lux and then reading a bright phone for an hour is a rounding error away from having done nothing at all.

Three things move that number, and only three: brightness, distance, duration. Drop the phone to the lowest setting you can still read, hold it further away, and stop earlier. A television across the room contributes far less at your eye than a handset at arm's length, which is why the tablet in bed is a worse problem than the film on at 9pm. A night mode that only warms the colour is a discount, not a fix: by the ratio table above it moves the multiplier by roughly half.

What I'd do

Set one warm lamp to the lowest level you can still read a paperback by, kill the ceiling light at the three-hour mark, and leave it that way for a week. A week is long enough to tell whether the room was the problem.

Then go and fix the daytime end, because the same recommendations put a floor under it: 250 lux melanopic EDI while you are awake in daylight hours. That is a window seat or a walk, not a brighter bulb. For scale, a very dark overcast day outdoors is around 100 lux and office lighting runs 320 to 500 lux, so an indoor day often sits under the floor while the evening sits over the ceiling. Both ends are worth the same effort.

Last, put the evening light somewhere it does not depend on the wall switch. The Houseland ring runs on either a plug-in mains adapter or AA batteries, so the layer can go on a wall with no socket near it, and the remote changes the level from where you are sitting. The rest of the wall art is worth sizing against your own wall first, since this piece measures 47 in (120 cm) across including the shelf overhang and 27.6 in (70 cm) tall.

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