Sleep is essential – researchers are trying to work out why

Summary

Reactive oxygen species in the guts of flies glow depending on the concentration of the molecules.Credit: Alexandra Vaccaro and Yosef Kaplan DorWhen neurobiologist Dragana Rogulja began studying sleep in her laboratory at Harvard Medical School in Boston, Massachusetts, in 2013, she had no idea what her experiments would tell her about how sleep affects the body. She wasn’t assuming — as many people do — that it’s a function mainly of the brain. She was just starting her lab and decided to throw the net wide, asking the question: if animals are sleep deprived, how long will it take until they die — and when they die, what is the specific cause?She expected it would take years to answer these questions. But in six months, Rogulja’s postdoctoral assistant, Alexandra Vaccaro, found a tantalizing clue.“We started looking at lifespan and saw that the moment when sleep-deprived animals would start dying was pretty much always the same,” Rogulja says. “When they lost about 90% of their sleep each night, they started dying within about ten days.” Those studies were in flies and mice — but the implications for other animals, including humans, was intriguing.The average adult spends more than 20 years of their life sleeping, and the consequences of not getting enough are clearly harmful. But surprisingly little is known about why it’s necessary. That is, in part, because only in the past couple of decades have the tools become available to help scientists to understand the fundamental biological function of sleep. These include optogenetics, which involves directing laser light to specific neurons to wake a person or put them into deep sleep, and focused ultrasound, which has emerged in the past five years as a way to view the deep-brain neural oscillations that occur during sleep.With the help of such tools, researchers are beginning to understand that sleep does more than just give our brains and bodies a respite from the rigours of the day. When we sleep, our genes, metabo...