Good bedroom lighting for sleep comes down to three things in the evening: keep it dim, keep it warm in colour, and keep it low. A bedside lamp with a warm bulb of modest brightness does more for sleep than any "sleep light" gadget, and the big ceiling light is best left off after about 9pm.
In the morning, you want the reverse: bright light, ideally daylight, as soon as you can manage it. The two halves work together. Your body clock takes its cue from the contrast between a bright day and a dim evening, and modern homes tend to flatten that contrast at both ends.
This guide covers what to change, bulb by bulb, without turning your bedroom into a cave.
What evening light does to your body clock
Light-sensitive cells in the eye report brightness to the brain's master clock. Bright light in the evening tells that clock the day is still going, which delays the release of melatonin, the hormone that signals night, and pushes your natural bedtime later. Dim light lets melatonin rise on schedule.
Two features of light matter here. Brightness is the bigger one: a bright warm-white ceiling light still delays melatonin. Colour matters too, because the cells that feed the body clock are most sensitive to blue-rich light, the kind produced by daylight, cool-white LEDs and screens. A study by Chang and colleagues (2015) found that reading on a bright, blue-rich screen in the evening delayed melatonin and left people less alert the next morning compared with reading a printed book.
None of this means a lamp in the evening will wreck your sleep. It means the lighting most of us default to, a bright overhead light plus a phone, is working against the wind-down you are trying to create.
In short: Dim and warm in the evening, bright in the morning. Brightness matters more than colour, so lowering the light does most of the work.
Choosing bulbs: what the numbers mean
Bulb packaging in the UK gives two useful figures.
Lumens measure brightness. A typical ceiling bulb is 800–1,500 lumens. For an evening bedside lamp, something around 200–400 lumens is plenty for reading and low enough not to feel like daytime.
Colour temperature is given in kelvin (K). Lower numbers are warmer and more orange; higher numbers are cooler and bluer. Daylight is around 5,000–6,500K. "Cool white" bulbs are 4,000K and up. "Warm white" is usually 2,700K, and "extra warm" or "candle" bulbs are around 2,200K. For bedroom lamps, 2,700K or lower is a good choice.
A dimmable bulb, or a lamp with a dimmer, lets you use one fitting for both reading and winding down. Check that the bulb, the lamp and any dimmer switch are all marked as dimmable; a non-dimmable LED on a dimmer flickers and fails early.
Smart bulbs that shift from cool to warm through the evening are a convenience rather than a necessity. A warm bulb on a simple plug-in timer, or just the habit of switching from ceiling light to lamp after dinner, achieves most of the same thing for a fraction of the cost.
Position: keep light below eye level
Where the light comes from matters as much as how bright it is. Light from above, at the angle of the midday sun, is the pattern your visual system reads as daytime. Light from low down, at the level of a table lamp or a fire, is closer to what a body clock expects in the evening.
Practically, that means:
- Use lamps rather than the ceiling light in the last hour or two before bed.
- Put them at or below the height of your head when sitting or lying in bed.
- Point shades downwards or use opaque shades that throw light on a surface rather than into your eyes.
- If you need a night light for trips to the bathroom, a very dim, warm plug-in light at skirting-board height is far better than the landing light.
Bathrooms are the usual weak point. A bright, cool bathroom light at 11pm is a small jolt of daytime. If you can, brush your teeth by a lamp or a low-level light, or simply leave the door ajar and use the light from the hall.
Reading in bed
Reading before bed helps many people switch off, and a bedside lamp is the right tool for it. The aim is enough light to read comfortably without strain, aimed at the page rather than at your face. A warm bulb at around 300 lumens, a shade that directs light downwards, and the lamp on the side you hold the book, is about right. There is more on whether reading before bed helps sleep in our separate guide.
If you read on a device, turn the brightness right down, use dark mode, and switch on the warm colour setting most phones and tablets now have. It is less good than a lamp and a paper book, but a good deal better than a bright screen. Our guide to screens before bed goes into how much this actually matters.
Once the lights are off
After lights-out, the aim is darkness. Standby LEDs, a bright bedside clock and light leaking around curtains all count, and they matter more in the early hours, when sleep is lighter. A short audit and a few cheap fixes usually sort it; the guide to making your bedroom darker walks through them.
If you like a light on all night, keep it as dim and as warm as you can and place it away from the bed. Sleeping in a lit room is associated with lighter sleep in the research so far, though the effects of a very dim light are small.
Morning light: the other half of the job
The strongest single thing you can do for your body clock is get bright light soon after waking. Outdoor light, even on a grey British morning, is many times brighter than indoor lighting, so ten minutes outside, or breakfast by a window, sets the clock better than any bulb.
In winter, when you may be getting up in the dark, a sunrise alarm that brightens gradually before your wake time is a gentler start than a sudden alarm, and some people find it helps them feel awake sooner. The evidence is modest and mostly about how you feel on waking rather than sleep itself, but it is a reasonable thing to try if dark mornings are a struggle. Bright ceiling lights in the kitchen, the opposite of the evening advice, are exactly right at 7am. The guide to how your morning routine shapes tonight's sleep covers this in more detail.
A simple evening lighting routine
- After dinner, switch from ceiling lights to lamps in the rooms you use.
- In the last hour, keep to one or two warm lamps, below eye level.
- Use the dimmest light you can manage in the bathroom.
- Lights off means dark: cover LEDs, close curtains fully.
- In the morning, open the curtains straight away and get outside if you can.
None of this needs new fittings. A couple of warm, dimmable bulbs and a change of habit cover most of it, and the rest of the Sleep Environment guides cover temperature, noise and bedding if lighting turns out not to be the main issue.
Sources and further reading
- NHS Every Mind Matters: How to fall asleep faster and sleep better
- Proceedings of the National Academy of Sciences: Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS, 2015
- Sleep Foundation: Sleep Foundation
Written and reviewed by the Quiet Mind Sleep editorial team in line with our editorial policy. Spotted an error? Let us know.
