William Atkins
Friday, 24 April 2009 19:48
Science -
Biology
Page 2 of 3
The researchers used functional magnetic resonance imaging (fMRI) scans when performing the study, which analyzes blood flow and activity in various regions of the brain.
The team looked at people with extreme sleep and wake cycles. The very early risers in the morning were people who woke up between 4:00 and 5:30 a.m. in the morning, and the very late risers were those that woke around 12:00 noon.
They found that 66% of people woke up later than the very early risers and before the very late risers—that is what is considered the more normal times to wake up in the mornings.
The researchers used volunteers who spent two nights in a laboratory setting. They were awake and asleep depending on their own unique circadian cycles.
During this time, two fMRI scans were performed on each volunteer, one two hours after waking up and a second one 10.5 hours after waking up. During the two scans the volunteers performed a test to determine mental alertness.
The researchers found that the very early risers and the very late risers were both equally alert in the mornings. As the day progressed the early risers had reduced activity in the brain regions that controlled mental attentiveness—those areas involving the circadian master clock, which regulates alertness and sleep-awake cycles.
They also performed mental tests less efficiently than late risers.
In addition, during the evenings, the early risers felt more tired and performed less efficiently on the mental tests than the late risers.
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