(ORDO NEWS) — Researchers at Kyushu University stated that the need for sleep in animals appeared before the brain developed. Hydras pushed them to such conclusions – tiny freshwater creatures that do not have a brain, but at the same time sleep.
The need for sleep is universal for almost all mammals, insects and even roundworms. But until now, scientists do not know for sure whether the evolution of the brain preceded the evolution of sleep or vice versa.
New research has shown that hydras have cycles of active and sleep states – they last for four hours. In addition, if the animals are awakened, they show signs of lack of sleep – cell growth slows down, and in the next cycle it takes them more time to “get enough sleep.”
In their experiments, scientists also exposed hydras to chemicals that are involved in regulating sleep in humans. Some acted on animals as stimulants, others as a sedative.
“Our research has shown that animals acquired sleep-related mechanisms prior to the evolutionary development of the central nervous system. Many of these mechanisms persisted as the brain developed,” the scientists say.
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