The Winter Light Protocol
Every autumn the same thing happens: days get shorter, you leave for work in the dark, come home in the dark, and spend nearly all remaining daylight indoors. The light you live under drops from thousands of melanopic lux outdoors to a small fraction of that indoors — and your body notices, because the circadian system is calibrated to daylight, not to ceiling fixtures.
This protocol is part of our Human-Centric & Circadian Lighting methodology ; the science background is in our Circadian Lighting Guide and the melanopic EDI explainer .
How much daylight does your city lose?
Day length from standard solar geometry for your latitude. Approximate — presented in whole minutes, not clock-precise sunrise times.
Shortest day (Dec 21)
9 h 15 min
vs 15 h 06 min on Jun 21 — 5 h 50 min less
Daylight outside a 9:00–17:00 indoor day
1 h 15 min
on Dec 21, if you're indoors through standard working hours
Midday sun height (Dec 21)
26°
above the horizon — vs 73° in June
Day length through the year (21st of each month), today ≈ 11 h 13 min
The biological context: outdoor daylight delivers thousands of lux of melanopic light even under overcast winter sky, while published field studies show that many people in modern indoor environments receive daytime melanopic EDI below the 250 lux level recommended by the 2022 expert consensus (Brown et al., PLOS Biology). If all your winter daylight falls inside working hours, indoor lighting is the only circadian signal you get.
The protocol
Four rules, drawn from the published consensus recommendations on daytime, evening and night-time light exposure. None of them require willpower — they require the right light in the right rooms.
1 — Morning
Prioritize strong light exposure in the morning
Daylight outdoors is ideal, even overcast. During dark winter mornings, bright, blue-rich electric light (5000–6500 K, high melanopic content) at eye level helps increase daytime light exposure when natural daylight is unavailable.
2 — Daytime
Hold ≥250 lux melanopic EDI at eye level
That's the consensus daytime recommendation — and a level most interiors miss by a wide margin. High melanopic-efficacy spectra reach it at moderate photopic illuminance; lower-melanopic warm-white sources may require substantially higher photopic illuminance to reach the same melanopic EDI.
3 — Evening
Shift warm and dim at least 3 hours before bed
Drop to warm, low-melanopic light (1800–2700 K) starting at least 3 hours before habitual bedtime — the consensus recommends ≤10 lux melanopic EDI in the pre-sleep hours. Flame-like dim-to-warm spectra are designed for low-melanopic evening lighting.
4 — Night & consistency
Darkness at night, same schedule daily
Keep sleeping spaces as dark as practical, use minimal warm light for navigation, and keep wake and light timing consistent — regularity matters as much as intensity.
This page describes architectural lighting practice based on published circadian research and consensus recommendations. It is not medical advice. Seasonal affective disorder is a medical condition — if that's what you're experiencing, clinical light therapy and professional guidance are the right path, not a lighting remodel.
The hardware for each step
SunWave™
Full-spectrum, high melanopic-efficacy daytime light — steps 1 and 2.
Tunable White
A flexible platform for changing CCT and output through the day as part of a circadian lighting strategy.
Dim-to-FlameWarm™
Flame-spectrum evenings, low melanopic content — step 3.
Frequently Asked Questions
How much daylight do I actually lose in winter?
It depends on latitude. At 41°N (New York, Chicago) the day shrinks from about 15 hours in June to just over 9 hours in December. At 60°N (Oslo, Helsinki) it drops below 6 hours. Use the calculator above for your city.
Is normal indoor lighting enough during winter?
Usually not, biologically. Published field studies show that many people in modern indoor environments receive daytime melanopic EDI well below the 250 lux level recommended by the 2022 scientific consensus (Brown et al., PLOS Biology). Outdoor daylight, even on an overcast winter day, delivers thousands.
Is this the same as SAD light therapy?
No. Seasonal affective disorder is a medical condition; clinical light therapy uses dedicated devices under professional guidance. This page is about ambient architectural lighting that supports a normal day-night cycle — it is lighting design, not a medical treatment. If you suspect SAD, talk to a clinician.
What color temperature should winter lighting be?
It should change through the day: bright, blue-rich light (5000–6500 K, high melanopic content) in the morning and daytime, then warm, low-melanopic light (1800–2700 K) in the last hours before sleep. A static CCT cannot do both — which is why tunable-white and dim-to-warm systems exist.
Designing a winter-proof lighting scheme?
Tell us about the space — our engineering team can help you specify melanopic targets, spectra and control for a circadian-supportive design.