Going outside, even on a cloudy day, provides significantly more photon energy than typical indoor lighting, aiding circadian clock setting.

“There's about 1,000 lux, it seems really bright, but a cloudy day outside will have five times more photon energy coming through.”

“Going outside even on a cloudy day could be 7,000, 10,000 lux. It's really remarkable how bright it is, meaning how much photon energy is coming through.”

“But that natural sunlight is even on a cloudy day in England is usually far more potent than anything that you'll get from indoor lighting, despite you thinking sort of from a perception wise, maybe the much closer than I would think.”

“So, I have to tell you, the cloudiest day is going to be much more brighter than your room. You could ask any photographer. A cloudy day, unless it's really dark, dark clouds, usually cloudy days have much more light outside than inside the room, even when you have good lighting inside the room.”

“even on a cloud-covered day, you are going to get far more light energy, photons through cloud cover than you are going to get from an indoor light source, an artificial light source.”