“Lithium tweaks many mood-altering chemicals in the brain, and its effects are complicated. Most interesting, lithium seems to reset the body’s circadian rhythm, its inner clock. In normal people, ambient conditions, especially the sun, dictate their humors and determine when they are tuckered out for the day. They’re on a twenty-four-hour cycle. Bipolar people run on cycles independent of the sun. And run and run.”
