What's going on in the brains of people who don't need much sleep?

Many people claim that they don't need much sleep, insisting that even five hours a night is enough shuteye for them to feel rested. According to new scientific research, "habitual short sleepers" may actually be handling the brain tasks that most of us deal with during the night, like memory consolidation. From Medical Xpress:

Both groups of short sleepers exhibited connectivity patterns more typical of sleep than wakefulness while in the MRI scanner. (University of Utah radiologist Jeff) Anderson says that although people are instructed to stay awake while in the scanner, some short sleepers may have briefly drifted off, even those who denied dysfunction. "People are notoriously poor at knowing whether they've fallen asleep for a minute or two," he says. For the short sleepers who deny dysfunction, one hypothesis is that their wake-up brain systems are perpetually in over-drive. "This leaves open the possibility that, in a boring fMRI scanner they have nothing to do to keep them awake and thus fall asleep," says (Utah neurologist Chirstopher) Jones. This hypothesis has public safety implications, according to Curtis. "Other boring situations, like driving an automobile at night without adequate visual or auditory stimulation, may also put short sleepers at risk of drowsiness or even falling asleep behind the wheel," he says.

Looking specifically at differences in connectivity between brain regions, the researchers found that short sleepers who denied dysfunction showed enhanced connectivity between sensory cortices, which process external sensory information, and the hippocampus, a region associated with memory. "That's tantalizing because it suggests that maybe one of the things the short sleepers are doing in the scanner is performing memory consolidation more efficiently than non-short sleepers," Anderson says. In other words, some short sleepers may be able to perform sleep-like memory consolidation and brain tasks throughout the day, reducing their need for sleep at night. Or they may be falling asleep during the day under low-stimulation conditions, often without realizing it.

The next phase of the team's research, to be conducted at the University of Utah, will directly test whether short sleepers who deny dysfunction are actually doing fine. "Most people who are deprived of sleep show cognitive impairment similar to being intoxicated," Williams says.

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