Sleep science
Why Light Colour Matters at Night
Your body uses light as its primary signal for regulating the sleep-wake cycle. The pineal gland responds to light detected by the retina, producing melatonin — the hormone that makes you feel sleepy — mainly in the dark. When light enters your eyes at night, melatonin production slows or stops.
Not all light is equal. Research has shown that blue-wavelength light (400–480 nm), which is prominent in phone screens, LED bulbs, and most digital clocks, is particularly effective at suppressing melatonin. Amber and red light (above 590 nm) has a significantly reduced effect on the circadian system.
This is why GlowClock's night mode uses warm amber tones rather than the default white or cool-blue displays found on most clocks and phones. Checking the time in the middle of the night with a white-lit screen can signal your brain that it's daytime — making it harder to fall back asleep.
🔴 Amber & Red Light
Minimal impact on melatonin. Safe to use as a bedside clock. Your circadian rhythm remains largely undisturbed.
🔵 Blue & White Light
Strongly suppresses melatonin. Common in phones, tablets, and LED clocks. Can delay sleep onset significantly.
💡 Brightness Matters Too
Even amber light at very high brightness can affect sleep. Always combine night mode with low screen brightness for best results.
🌙 Dark Adaptation
After 20 minutes in darkness, your eyes become far more sensitive. This is why a brief flash of light feels so intense when you wake at night.
The blackout feature in GlowClock addresses this directly. Rather than leaving a dim glow on all night, the screen goes fully dark between time checks. This keeps your room in true darkness — better for both partners, and for your own melatonin levels throughout the night.