It’s a crummy situation. You were up a little too late and you have to be up early for work. Around 2:30AM for seemingly no reason, you jolt awake and stay that way for about an hour. This makes for a pretty groggy Wednesday morning, huh? It may really stink to wake up like that, but it’s actually actually an old, evolutionary trait.
If you often wake up in the middle of the night, it’s actually because you’re supposed to. Humans used to do what’s called “segmented sleep,” which sounds exactly like what it is. We slept for four hours, woke up for one or two, then slept another four. It’s a natural biological clock that we have learned to ignore.
People once used that hour in between sleeps to pray, to write, to drink some tea or just relax some other way. During this time, the brain produced prolactin, which is a hormone that promotes relaxation.
“For most of evolution we slept a certain way. Waking up during the night is part of normal human physiology,” says psychologist Greg Jacobs. “The idea that we must sleep in a consolidated block could be damaging, he says, if it makes people who wake up at night anxious, as this anxiety can itself prohibit sleep and is likely to seep into waking life too.” Russell Foster, a professor of circadian neuroscience at Oxford backs up Mr. Jacobs’ assertion. “Many people wake up at night and panic,” says Foster. “I tell them that what they are experiencing is a throwback to the bi-modal sleep pattern. But the majority of doctors still fail to acknowledge that a consolidated eight-hour sleep may be unnatural. Over 30% of the medical problems that doctors are faced with stem directly or indirectly from sleep. But sleep has been ignored in medical training and there are very few centers where sleep is studied.” So before you look to diagnose the problem, consider that it’s just your body doing what it naturally does.