The human eye can detect a single photon of light. In evolutionary terms, light meant daytime, danger, and the need for alertness. Even modern low-level light — a phone screen in standby, a streetlight through curtains — is enough to suppress melatonin production by up to 50%.
Lux levels matter
At 10 lux (approximately a dimly lit room), melatonin suppression begins within 20 minutes of exposure. Most bedrooms sit between 15 and 80 lux when accounting for standby indicator lights, digital clocks, and light pollution through windows.
Complete darkness — below 1 lux — is the environment your circadian system was calibrated for.
The 14-minute difference
In our testing, participants using a complete-seal, 3D-contoured eye mask fell asleep an average of 14 minutes faster than those in a dimmed but unmasked room. Over a year, that’s nearly 85 hours of extra sleep.
