Master Sleep Science
I don’t have these problems at home, and no wonder. Camping wreaks havoc on a finely calibrated body clock designed to make me sleepy at bedtime and wake me up refreshed in the morning. Here’s how it works under normal circumstances.
“Light sets the timer,” says Dr. David Schulman, director of the Emory Sleep Disorders Lab. The sun peeks through your shades, or your spouse flicks on a lamp, shooting light through partially cracked lids and signaling your optic nerve to stimulate a part of your brain called the suprachiasmatic nucleus, or SCN. The SCN sends out an alert to wake you up, and stops the production of melatonin, the body’s primary sleep-inducing hormone. Basically, the SCN is the body clock, ruling our daily routines by releasing and inhibiting the right brain chemicals at the right times.
From that moment–even though you’re wide-awake–the pieces for your next good night’s sleep are already being put in place. With every hour, your “sleep drive” (jargon for your desire to nod off) builds. Scientists aren’t sure about the exact hormonal ingredients that make up the sleep drive, but recent studies point to a chemical called adenosine as a major player. As your cells use energy, adenosine accumulates in your bloodstream. The more there is, the sleepier you get. Your body then breaks down the backlog while you snooze, and you start afresh the next morning. (Feel groggy in the morning? You probably haven’t slept long enough to break down all the adenosine.) You might think we’d all get increasingly exhausted as sleep drive grows throughout the day–and you’d be right, except that the brain counters that drive with an even stronger dose of a stimulating chemical that scientists call the alerting signal.
Until darkness falls, that is. When the lights go out and the signal gets turned off, you’re left defenseless against a day’s supply of sleep drive. On top of that, the pineal gland starts cranking out melatonin, which helps you fall asleep and stay that way through the night. Sleep becomes irresistible; you drop off, dream, and repeat until the cycle starts up again in the morning.
The complex dance of alerting signal and sleep drive follow a pattern: Your body’s natural tendency is to fall asleep and wake up at about the same times each day, ensuring you get your requisite seven to nine hours. But we all know it’s rarely that simple: Stress, excitement, physical exertion, alcohol, caffeine, even late-night s’mores can knock the body clock out of whack. And when you consider that all of the above can be part of any backpacking trip–with the addition of an unfamiliar setting and an uncomfortable bed–can you blame me for tossing and turning?