How light controls your sleep clock
Your body reads light, particularly blue wavelengths, as a signal that it's daytime. This suppresses melatonin, the hormone that makes you feel sleepy. Screens, but also bright overhead lighting in general, can delay melatonin release well into the evening.
Where the blue-light story gets oversimplified
Screen brightness and viewing distance matter as much as the blue light itself - a phone six inches from your face at full brightness has a much bigger effect than a TV across the room. Content matters too: a stressful email at 11pm keeps you alert regardless of the light involved.
What actually helps
- Dim household lighting generally in the hour before bed, not just screens
- Blue-light filtering glasses if screen use in the evening is unavoidable
- A consistent low-light wind-down cue your body learns to associate with sleep
- Morning daylight exposure - this regulates your body clock more than evening light avoidance alone
Melatonin supplements: use with care
Melatonin can help reset a disrupted schedule, particularly with jet lag, but it's a hormone, not a sedative, and more isn't better - low doses (0.5-1mg) taken at the right time tend to outperform higher doses. It works best alongside good light habits, not as a substitute for them.