Sleep: How Long Can You Go Without It? (VIDEO, PHOTOS)

Sleep has intrigued scientists for a long time, but only within the last fifty years or so has it become a systematic area of study. In that amount of time, we’ve gained new insights into circadian rhythms and sleep cycles, including dream-laden REM—or rapid eye movement—sleep. And although we know a lot about how we sleep, exactly why we sleep is still a mystery.

One way scientists have attempted to answer the holy grail question of why we sleep is to study what happens when we don’t sleep. New research has shown that when animals don’t sleep for extended periods of time, certain neurons flip their own switches, in essence, and display sleep-like patterns of activation even in a wakeful individual. And interestingly, dolphins and seals sleep only one hemisphere of the brain at a time. Perhaps because they must come up for air—they are mammals, after all—and because they need to look out for predators, they have evolved an ability to sleep while they are still awake. If certain brain regions can be asleep and others awake at the exact same time, perhaps sleep isn’t the all-or-nothing phenomenon that scientists long thought it was. This paradigm shift in the way we view sleep may lead to new efforts in studying sleep disorders or lapses in attention from daytime sleepiness.

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