Avoid bright overhead light in the 2 hours before bed

Bright light after ~9 pm suppresses melatonin and shifts your clock later — dim the environment instead.

Why it works

The ipRGC–SCN pathway has a bidirectional phase effect: morning light advances the clock (earlier phase), while bright light at night delays it (later phase). Even relatively dim overhead indoor light in the late evening can significantly suppress melatonin onset and delay sleep timing. Dimming environmental light in the 2-hour pre-bed window preserves the melatonin rise and shortens sleep-onset latency.

How to do it

1. Switch to lamps below eye level or dimmed lighting after dinner.
2. Use night mode or orange-tinted glasses if screens are unavoidable.
3. Avoid overhead fluorescent or bright white LEDs in the last 2 hours before your target bedtime.
4. Test the change for one week and notice whether falling asleep becomes easier.

Evidence

Controlled lab studies show that room-level indoor light before bed suppresses melatonin onset and shortens melatonin duration compared to dimmer conditions. This is replicated, high-quality sleep physiology. (observational)

Most studies measure the acute physiological effect; long-term outcome trials specifically testing light-dimming routines as a behavioral intervention are limited.

Sources

• Gooley et al. (2011), exposure to room light before bedtime suppresses melatonin onset, Journal of Clinical Endocrinology & Metabolism

Common mistake

Focusing only on phone screens and ignoring much brighter overhead room lighting, which produces a larger melatonin-suppression effect than the screen itself.