Andrew Huberman· PhD
On a sunny day, so no cloud cover, provided that the sun is not yet overhead. It's somewhere low in the sky could have just crossed the horizon, or if you wake up a little bit later it could be somewhat low in the sky. Basically the intensity of light, the brightness, is somewhere around 100,000 Lux. Lux is just a measurement of brightness. On a cloudy day it's about 10,000 Lux. Okay. So tenfold reduction. But bright artificial light, very bright artificial light is somewhere around 1000 lux. And ordinary room light is somewhere around 100-200 lux.