Each person has an internal biological clock that determines his own personal sleep/wake cycle. Called circadian rhythm, your individual 24-hour clock determines whether you’re an early riser or a night owl (see our April 24 post). Interestingly, new research conducted by researchers in Brussels, Belgium indicates that people who wake later in the morning, 9 a.m. as opposed to 5 or 6 a.m., remain more alert for longer periods during the day, even if they turn in early.
In tests comparing the sleep cycles of early birds and night owls, MRI brain scans were taken to measure brain activity at different times throughout the day and night. Night owls were slower than early risers to exhibit sleep pressure (the urge to sleep) as the day progressed, remaining alert for one to two hours longer per day than early risers. Eventually though, the study found that night owls paid a price for their late hours. Out of synch with society’s daily schedule (children, school, job schedules, etc.), night owls tended to rack up a sleep deficit as the week progressed, requiring additional sleep on the weekends to recover.
Similar studies in the U.S. have shown that teenagers who typically prefer staying up late and sleeping in might do better in school if the school day started later and went longer. Some school districts are considering switching high school schedules to accommodate teenage circadian rhythms. In recent trials, starting high school classes at 9 a.m. and ending at 5 p.m. to 6 p.m. resulted in more alert students and improved academic performance.
While the exact role of sleep is still under debate, director of the Belgium study, Philippe Peigneux, professor of clinical neuropsychology at the Free University of Brussels explained in an article posted to The Why? Files website that researchers are convinced that an activity at which you spend fully one-third to one-quarter of your life — sleep — must have multiple functions critical to the health of mind and body. “When you fall asleep, you are not conscious of the external world, but sleep helps restore your ability to be alert the next day. Sleep is believed to be important for thermal regulation and memory consolidation, and many other functions,” he said. Continuing research will determine what other roles sleep plays in good health.
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