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Sleep is a mystery. It’s essential — without enough sleep, we die — and yet scientists still aren’t sure why we need it.

But the how of sleep is just as intriguing as the why.

Amita Sehgal, a sleep researcher at the University of Pennsylvania, has discovered some of the key genes that control our 24-hour circadian cycle, making us fall asleep at night and rise again in the morning. Sehgal didn’t find these genes in people, however. She found them in flies.


Flies, it turns out, sleep too, and their sleep is astonishingly similar to our own. Deprive a fly of sleep, for example, and it will need to catch up with some extra slumber. These similarities are the result of sleep’s deep evolutionary history. Our microbial ancestors had primitive circadian rhythms, and early animals 700 million years ago used those cycles to control their sleep rhythms.

Today, flies and humans use many of the same genes for sleep. By breeding thousands of flies, Sehgal hopes to discover more of the genes for sleep, and use what she learns from insects to help give humans a good night’s rest.


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