How Did an Earlier Cortisol Pulse Ease Depression?

Andrew Huberman says morning light exposure triggers dopamine release. He calls dopamine part of the reward system and the molecule of motivation and positive anticipation. A cortisol pulse arrives once every 24 hours no matter what. The rhythm is intrinsic, and viewing light or exercising early in the day can time it.

David Spiegel, associate chair of psychiatry at Stanford, co-published with Bob Sapolsky. They showed that a cortisol pulse later in the day, especially around eight or nine PM, is associated with depression. Shifting the pulse earlier in the day ameliorates some of the symptoms of depression, and the dopamine release brings an overall mood enhancement.

He names four timekeepers for circadian biology, mood, and sleep. Light is the most powerful, then exercise, then feeding, then social cues such as people or a dog early in the day. Miss one day and the body still sends an early alertness signal, because it learns to anticipate the cues. Doing the cues every day is like setting a watch.