The Light You're Not Blaming for Bad Sleep
Why ordinary room lighting, not just screens, is the bigger issue
Evening light gets discussed almost entirely in terms of phone and laptop screens. The research points to something broader: ordinary indoor room lighting is itself a significant, underappreciated factor.
Room Light Alone Suppresses Melatonin
Melatonin is the hormone that signals to your body that biological night has begun — it rises in the evening and stays elevated through sleep. A controlled study comparing melatonin levels under dim light versus ordinary room light in the hours before bedtime found that typical indoor room lighting — not screens specifically, just standard overhead and lamp lighting — significantly suppressed melatonin onset and shortened the overall duration of elevated melatonin compared to dim lighting, with the effect persisting into the sleep period itself for some participants[4]. This matters because most evening-light advice focuses narrowly on screens, when ordinary bright room lighting in the hours before bed is doing meaningful damage on its own.
Why Timing and Colour Both Matter
Timing: the closer to your habitual bedtime, the more disruptive bright light tends to be — the biological "evening" (from your circadian clock's perspective) is when melatonin release is meant to be ramping up.
Colour temperature: given ipRGCs' blue-light sensitivity (Section 1), warm-toned lighting (amber, orange, red-shifted) provides a weaker circadian signal than cool white or blue-toned light at the same overall brightness — which is the reasoning behind switching to warm lamps rather than overhead white lighting in the evening.
Overall brightness still matters regardless of colour — a very bright warm-toned light will still suppress melatonin more than a dim one, so dimming and warming are complementary strategies, not substitutes for each other.
The Practical Routine
Dim overhead lighting after sunset and favour lamps over ceiling lights; switch to warm-toned bulbs in rooms used in the evening; and reduce bright screen exposure in the hour or two before bed where practical. None of this requires darkness — it requires meaningfully lower brightness and warmer colour than daytime lighting, which is a much easier standard to hit consistently.
Section takeaway
Ordinary room lighting, not just screens, measurably suppresses melatonin in the hours before bed — dimming and warming your evening environment generally is a more complete fix than screen-specific interventions alone.