Sleep chronotype: How the body clock controls sleeping, waking cycles

Early to rise makes a person healthy and wise? Not necessarily.

Depending on how your body clock is wired, the opposite may be true!

Every person’s body is set to follow daily patterns, including one for sleeping and waking.

“They’re controlled by your body clock, which is an innate structure in your brain that regulates how those things change during the day,” said Patricia S. Daniels, a National Geographic contributing author who explored how the body clock affects the sleep-wake cycle for the magazine’s Mind Body Wonder series.

She said the body clock consists of a group of neurons in the brain that connects to other structures, including the parts that release hormones.

“Melatonin is the one that a lot of people know. Sometimes people take melatonin to help them get drowsy,” she said.

This schedule is so hardwired that it’s not necessarily dictated by external cues, like light. In 1938, researchers who camped out for 32 days in total darkness followed regular cycles of sleep and body temperature.

“They slept. They woke. They ate their meals on a pretty regular daily schedule, whether they knew what time it was or not,” Daniels said.

Each person’s body clock is set a little differently for their individual sleep-wake cycles. This innate and genetic characteristic is called a chronotype.

Around one-fourth are the night owls, people who go to bed late and wake up late. Another 25% have the opposite disposition: the larks, or early birds.

“And then roughly 50% of us fall somewhere in the middle. We may sleep from 10 [p.m.] to 7 [a.m.] … and most of society operates to keep those people happy. “

Daniels said no one chronotype is healthier than another. Instead, people should learn from their own body rhythms, examining when they feel most productive and upbeat.

“If you have the luxury of doing that, you can really tailor your life to your own body type, and it makes your life a little better,” Daniels said.

“The other takeaway I have from this research is simply how important sleep is, whether you’re an owl or a lark,” she added.

The body clock controls much more than sleep. Learn how it manipulates everything from athletic performance to mood and appetite at NatGeo.com/health.

The Walt Disney Co. is the parent company of National Geographic Partners and this ABC station.