By Trent Houlahan · Director, Northern Currents Electrical
Most people know blue light affects sleep. Fewer realise the biggest source in the evening usually isn't the phone — it's the ceiling. Standard LED downlights emit significant blue-spectrum light right up until the moment you switch them off, and your brain treats that light as a midday signal.
Your eyes contain specialised photoreceptors (ipRGCs) that don't contribute to vision — their job is telling your brain's internal clock what time it is. They're most sensitive to short-wavelength blue light, around 480nm, which is abundant in daylight and in cool-white LEDs. When they detect it, your brain suppresses melatonin, the hormone that initiates sleep. Research published in the Journal of Pineal Research found two hours of evening blue-enriched light delayed melatonin onset by around half an hour. Do that nightly and you've shifted your entire sleep schedule without noticing.
It's the last lit room you're in. A 4000K downlight over the bed delivers a wake-up signal minutes before you try to sleep, and bathroom lighting — often the coolest, brightest in the house — is typically the very last light you see. The room you most need to be melatonin-safe is usually the least.
Change the globes. Swap bedroom and bathroom globes to 2700K or warmer. For the hour before bed, amber (around 1800K) is the standard to aim for — studies of amber-spectrum light at this colour temperature show little to no measurable melatonin suppression. Cost: a few dollars per globe.
Add a lamp layer. Stop using ceiling lights after dinner entirely. Two warm lamps at eye level or below change the character of a room and roughly halve the light hitting your eyes. No electrician needed.
Dim properly. Dimming helps, but only with compatible dimmers and drivers — a mismatched pair flickers, buzzes, and often can't dim low enough to matter. This is where fittings chosen for CRI and flicker performance earn their keep.
Wire it so it's automatic. The durable solution is lighting that changes by itself: warm zones for evening circuits, tunable fittings that track the day, amber night-path lighting for kids' rooms and hallways. That's an electrical design job — and it's the difference between fighting your house nightly and never thinking about it again. Our circadian lighting page covers what's involved, including an interactive guide to colour temperature.
Lighting is one input among several — caffeine, stress, screens, and schedule all matter. But it's the input wired into your walls, it affects everyone in the house every night, and it's fixable once, permanently. That's why we start there.
From globe advice to full circadian design — we'd love to help.