For most of human history, evenings got darker and warmer: sunset, then firelight. Today most homes run the same bright, cool-white light at 10pm as at noon.
Light is a signal, not just illumination
Your brain's master clock uses light reaching your eyes to judge the time of day. Bright light, especially in the blue-green range, says "daytime". Darkness says "evening", and your body begins releasing melatonin.
In a 2011 study of 116 adults, ordinary room light in the hours before bed shortened melatonin duration by about 90 minutes compared with dim light (Gooley et al., Journal of Clinical Endocrinology & Metabolism).
The fix is simple
- At sunset, switch off overhead lights.
- Use one or two low lamps with warm bulbs.
- Dim your screens, or put on amber glasses two hours before bed.
- If you need light in the night, keep it dim and red.
You don't need to live in the dark, just let your home follow the sky.
Educational content, not medical advice. If you have ongoing trouble sleeping, talk to your doctor.