Here’s what’s supposed to happen when you fall asleep. Your body temperature falls, even as your feet and hands warm up—the temperature changes likely help the circadian clocks throughout your body to synchronize. Melatonin courses through your system—that tells your brain it’s time to quiet down. Your blood pressure falls and your heart rate slows. Your breathing evens out. You drift off to sleep.
That, at least, is the ideal. But going to sleep isn’t always a simple process, and it seems to have grown more problematic in recent years, as I learned through a series of conversations this May, when some of the world’s leading sleep experts met with me to share their ongoing research into the nature of sleeping. (The meetings were facilitated by a Harvard Medical School Media Fellowship.) According to Charles Czeisler, the chief of the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital, over the past five decades our average sleep duration on work nights has decreased by an hour and a half, down from eight and a half to just under seven. Thirty-one per cent of us sleep fewer than six hours a night, and sixty-nine per cent report insufficient sleep. When Lisa Matricciani, a sleep researcher at the University of South Australia, looked at available sleep data for children from 1905 to 2008, she found that they’d lost nearly a minute of sleep a year. It’s not just a trend for the adult world. We are, as a population, sleeping less now than we ever have.
more here.