"Anchor your cortisol pulse early every morning When light hits the eye at low solar angle, it triggers a cortisol pulse that sets a 12-to-14-hour countdown to melatonin release — the brain's primary on/off switch for wakefulness and sleep. Huberman warns that a cortisol pulse delayed until evening "is one of the consequences, and maybe one of the causes, of a lot of anxiety disorders and depression." Consistently getting bright outdoor light early in your wakeful period, before the sun moves high overhead, locks this timing and produces downstream benefits including stable blood pressure, better mood, and easier sleep onset. Source: Andrew Huberman, Huberman Lab, Master Your Sleep & Be More Alert When Awake"