What Bulbs to Buy for Healthy Evening Lighting

I spent an embarrassing amount of time a couple of years back standing in the lighting aisle at Elkjøp with my phone out, photographing the little spec panels on the back of bulb boxes. Not because I'm that person (well, I am that person), but because I'd just realised that "warm white" means almost nothing. Two bulbs can both say "warm white" on the box and be doing completely different things to your evening biology. One useless, one fine. Same words. That's the bit nobody tells you when you're stood there at 6pm trying to make a decision before the shop closes.

For healthy evening lighting, look for bulbs rated 2700K or lower on the colour temperature scale, ideally down around 2200K or in the amber to red range. The Kelvin number on the box tells you roughly how much blue content the light has. Lower numbers mean less blue, less melanopsin stimulation, and less interference with your evening melatonin rise. "Warm white" alone isn't a reliable guide, you need the actual number, and the closer you get to bedtime, the lower it should be.

The one number that actually matters: Kelvin

Every lightbulb sold has a colour temperature, measured in Kelvin (K), printed somewhere on the box, sometimes in tiny print next to the lumens. Daylight is somewhere around 5000 to 6500K. A standard "cool white" LED, the kind that comes as default in a lot of cheap fittings, is often 4000K or higher. "Warm white" is usually somewhere between 2700K and 3000K. And then there's the stuff below that, 2200K, 2000K, down into the amber and red range, which is where things actually start to change for your evening biology.

The lower the Kelvin number, the less blue content the light has relative to red and amber. That matters because of a type of cell in your eye called an intrinsically photosensitive retinal ganglion cell (ipRGC), which contains a pigment called melanopsin, most sensitive to blue light around 460 to 480nm. When melanopsin gets activated in the evening, it tells your brain's master clock it's still daytime, and melatonin release gets delayed. A 4000K kitchen light on at 7pm is, as far as your circadian system is concerned, a fairly convincing impression of midday. Ask yourself now: what's on in your kitchen or living room right now at this time of evening?

The research: why "it looks warm" isn't the same as "it acts warm"

There's a study I think about a lot here, done in a real-world setting rather than a lab. Researchers exposed people to light from five different conventional household and office lamps for 30 minutes, an hour before their normal bedtime, and measured melatonin in saliva. Yellow light left melatonin essentially unchanged. But every lighting condition that included a blue component, including lamps described as "warm white", significantly reduced the melatonin rise, and people reported feeling more alert afterwards. You can read the full paper here: https://pmc.ncbi.nlm.nih.gov/articles/PMC3588003/.

A separate study compared 3000K and 6200K LED lighting at night in both children and adults. Both temperatures suppressed melatonin in children more than in adults, but the 6200K condition suppressed it significantly more than 3000K in children specifically. The children also reported feeling less sleepy under the bluer light. The researchers' conclusion was clear: lower colour temperature lighting at night is recommended, particularly for children. That one's here: https://pmc.ncbi.nlm.nih.gov/articles/PMC6295443/.

So the "warm white" 3000K bulb in your kid's bedroom is doing better than a 6200K one, but it's still not the same as something at 2200K or lower. The gap between "warm white" and "actually low blue" is bigger than the names suggest. This isn't about being obsessive. It's about understanding that the names on the packaging were written by marketing departments, not biologists.

Does red light actually help, or does it just not hurt?

Most of what I've covered so far is about avoiding harm. Lower blue content, less interference with melatonin. But there's a separate, smaller body of research suggesting red light specifically might do something more active. A study on elite Chinese basketball players had one group sleep with 30 minutes of red light exposure (658nm) every night for 14 days, and found not just better sleep quality scores, but a measurable rise in serum melatonin compared to the placebo group. You can read that one here: https://pubmed.ncbi.nlm.nih.gov/23182016/.

I wouldn't overstate this, it's one study in a specific population, and "does not suppress melatonin" is the well-established finding while "actively raises melatonin" is more tentative. But it does mean the choice isn't only between bad blue light and neutral amber. A proper red-toned bulb in a bedside lamp might be doing something slightly more useful than just staying out of the way. So which is yours doing right now? Getting in the way, staying neutral, or actually helping?

What this actually looks like in a Norwegian home

Think about those modern Norwegian homes (perhaps you're in one right now) with the recessed LED spotlights in the ceiling. Usually on a single switch. Usually somewhere around 3000 to 4000K because that's what came with the fitting and nobody's thought about it since. Bright, clean, even. Everything looks great and modern. Wonderful, but it is also the worst possible lighting to have on at full brightness at 9pm, and it is the default in an enormous number of Norwegian living rooms and kitchens.

Now, this isn't me being high and mighty about it. Most people have no idea this is a thing. I didn't either, for years. The packaging doesn't tell you, and nobody at Elkjøp is going to pull you aside and explain the melanopsin system. But once you know, it's a five-minute fix.

In order of effort. First, and most important: get the right bulb for the right time of day. Not a dimmer. Dimmers are often suggested for this but there's a problem with them. Most dimmers work by rapidly switching the bulb on and off to simulate lower brightness, which increases flicker, and that flicker can stress the eyes in ways you don't consciously notice. If you're trying to protect your evenings, the last thing you want is a light source that's pulsing invisibly at the back of your retina. The better solution is to have bulbs that are simply correct for the time of day, no dimming required.

For general evening use, no-blue-peak bulbs rated around 2700K or below make an immediate difference. These are built differently from standard LEDs, the blue spike in the spectrum is removed or reduced at manufacturing, not filtered down afterwards. For the last hour before sleep, that's where amber lighting comes into its own: proper amber-toned, not just warm white. And for the bedside lamp or any light on right before you close your eyes, a true no-blue-peak amber or red bulb is doing something more active than just not causing harm, as I mentioned in the section above about the basketball study.

I stock no-blue-peak bulbs, transition bulbs for moving between times of day, and amber lighting across different fitting types. All of them are in the circadian and sleep healthy lighting collection with the colour temperatures and blue peak information listed properly. If you're not sure which is right for which room, message me, that's the kind of thing I actually enjoy working through.

Where this fits with everything else

If you've read my post on bedroom light pollution and sleep quality in Norway, this is the daytime-into-evening half of that conversation. The bedroom post deals with what's happening once the lights are off. This is about what's happening while they're still on. And if you've got kids, the colour temperature point matters even more for them than for you. I went into that in more detail here: blue light free lighting solutions for Norwegian families.

This also connects to the blue light glasses conversation. Glasses are the backup plan for light you can't control, at work, at other people's houses, on screens late at night. Getting your own home right means you need that backup less often. I wrote about whether blue light glasses actually work here: do blue light glasses actually work.

Disclaimer: This post is for educational purposes and does not constitute medical advice. Lighting changes are one part of a broader sleep environment. If you're experiencing ongoing sleep difficulties, it's worth discussing with your doctor.

Frequently Asked Questions

What Kelvin rating should I look for in evening lightbulbs?

For general evening living spaces, aim for 2700K or lower. For the hour or so before bed, particularly bedside lamps, going lower still to 2200K or amber and red-toned bulbs gives you the biggest reduction in blue light content and the least interference with melatonin. The number is printed on the box, usually near the lumens figure.

Are "warm white" LED bulbs good enough for healthy evening lighting?

"Warm white" usually means somewhere between 2700K and 3000K. That's better than cool white at 4000K and above, but research shows it still contains enough blue content to measurably suppress melatonin, especially in children. It's a reasonable default for general living areas but not the best choice for the last hour before sleep.

Should I use a dimmer for evening lighting?

Dimmers are often suggested, but there's a catch most people don't know about. Most dimmers work by rapidly switching the bulb on and off to simulate lower brightness, which increases the flicker rate. That flicker can stress the eyes in ways you don't consciously perceive. The better approach is to have the right bulb for the right time of day: a no-blue-peak bulb for general evening use, and an amber or red bulb for the hour before sleep. You're not dimming your way to better light, you're choosing the right spectrum in the first place.

Where can I buy red or amber bulbs in Norway?

Standard home stores carry some low Kelvin options, but the selection of true red-toned bulbs, as opposed to just low Kelvin amber, is limited and rarely labelled clearly. The bulbs I've tested and actually stock are in the circadian and sleep healthy lighting collection, with the colour temperatures listed properly.

Hvilken lyspære bør jeg bruke om kvelden?

Se etter pærer merket 2700K eller lavere. For den siste timen før du legger deg, spesielt nattbordslampen, gir amber- eller rødtonede pærer ned mot 2200K den største reduksjonen i blått lys og minst forstyrrelse av melatoninet ditt. Kelvin-tallet finner du på esken, som regel i nærheten av lumen-tallet.

References

Münch M, Linhart F, Borisuit A, Jaeggi SM, Scartezzini JL. Out of the lab and into the bathroom: evening short-term exposure to conventional light suppresses melatonin and increases alertness perception. International Journal of Environmental Research and Public Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC3588003/

Melatonin suppression and sleepiness in children exposed to blue-enriched white LED lighting at night. Physiological Reports. https://pmc.ncbi.nlm.nih.gov/articles/PMC6295443/

Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. Journal of Athletic Training. 2012. https://pubmed.ncbi.nlm.nih.gov/23182016/