Light exposure is the primary regulator of circadian rhythm, with exercise, feeding, social factors, and temperature also playing roles.

“Light, temperature, timing of food intake, movement and exercise, all of these things literally funnel in in a neural sense, they funnel into this thing that we call the circadian clock and they let that clock, that set of neurons, predict when you are likely to be eating and active and viewing sunlight the next day and the next day and the next day.”

“And it's also impacted by things like when you eat, when you exercise, um temperature can affect it as well.”

“the biggest thing you can do for your circadian rhythms is watch every sunrise okay whether it's rain or shine the first light your eyes need to see in the morning should be the light from the sun”