Could something as ubiquitous as the lightbulb be a mixed blessing? Right in the middle of your brain sits the pineal gland, your so-called third eye. It’s connected to your actual eyes and has just one function: to produce a hormone called melatonin. During the day, the pineal gland is inactive. But once the sky darkens, it activates and begins pumping melatonin into your bloodstream. You start getting tired, feel less alert, and start thinking about sleep. Melatonin secretion may peak between 2:00 A.M. and 5:00 A.M. and then shuts off at daybreak, which is your cue to wake up.
