The short version:

Proper circadian rhythmicity and adequate secretion of melatonin at night play a major role in human wellbeing and health. You will sleep, look and feel better, be healthier and probably live longer.

Light is one of the most important factors for this. You want the right kind of light, at the right time:

Morning/day: Bright blue/white light

Evening/night: Dim, non-blue/orange light

Good sources of blue light:

  1. The Sun
  2. Blue-Light devices


In the evening, avoid blue light like this:

  1. Install f.lux on your laptop, activate night shift on iOS
  2. Wear blue blocker sunglasses, like these: