Night Owls vs. Early Birds: Who Sleeps Best?
Some people are night owls, others rise with the birds. Each person moves to his own circadian rhythm; his internal biological clock determining when he’s most alert and when he can’t keep his eyes open. While nurses, night watchmen, third shift workers and others who work at night can learn to retune their body clocks, it’s difficult to go against Mother Nature. A new study shows that while the early bird may get the worm, early risers get sleepier faster as they move through the day than people who get up later in the morning.
“The circadian signal is low in the morning, and increases during the day, helping to counteract the accumulation of sleep pressure,” explained Philippe Peigneux, professor of clinical neuropsychology at the Free University of Brussels in Belgium in an article posted to The Why? Files website. “At the end of the day, you have a lot of sleep pressure, and because the circadian signal starts diminishing at that time, eventually sleep can take place.”
While circadian rhythm is unique to each individual, it follows a basic 24-hour pattern of wakefulness and sleep that sets the individual’s body clock. Signals from the suprachiasmatic nucleus of the brain controlling the rise and fall of body temperature, immune activity, and signal wakefulness and sleep. The new study measured the balance between sleep pressure, the body’s need to sleep, and the body’s alerting signal that triggers wakefulness in two groups of people with natural circadian rhythms at opposite ends of the sleep spectrum: early birds and night owls. Overseen by Peigneux, the study was conducted by Ph.D. student Christina Schmidt of the University of Liege. Schmidt tracked test subjects in a sleep lab for two nights, periodically scanning brain wave activity to measure sleep pressure and alertness.
The study found that when we awaken both sleep pressure and the body’s alerting signal are low. From the point of wakefulness, both brain signals increase gradually throughout the day, reaching a peak about 15 hours later when the alert signal quickly falls off, allowing the body to become drowsy. At the same time, sleep pressure peaks, becoming greatest just prior to and during the first two hours of sleep before tapering off dramatically 8 to 10 hours later. While study results indicated that both early birds and night owls experienced similar quantities and quality of sleep, early birds exhibited more slow brain waves throughout the day, indicating a greater need for sleep than night owls.
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