UCLA-led team of scientists discovers why we need sleep

https://www.eurekalert.org/pub_releases/2020-09/uoc--uto091420.php

News Release 18-Sep-2020


In very early life, sleep helps build the brain's infrastructure, but it then takes on an entirely new decluttering role

University of California - Los Angeles

Prolonged sleep deprivation can lead to severe health problems in humans and other animals. But why is sleep so vital to our health? A UCLA-led team of scientists has answered this question and shown for the first time that a dramatic change in the purpose of sleep occurs at the age of about 2-and-a-half.

Before that age, the brain grows very rapidly. During REM sleep, when vivid dreams occur, the young brain is busy building and strengthening synapses -- the structures that connect neurons to one another and allow them to communicate.

"Don't wake babies up during REM sleep -- important work is being done in their brains as they sleep," said senior study author Gina Poe, a UCLA professor of integrative biology and physiology who has conducted sleep research for more than 30 years.

After 2-and-a-half years, however, sleep's primary purpose switches from brain building to brain maintenance and repair, a role it maintains for the rest of our lives, the scientists report Sept. 18 in the journal Science Advances. This transition, the researchers say, corresponds to changes in brain development.

All animals naturally experience a certain amount of neurological damage during waking hours, and the resulting debris, including damaged genes and proteins within neurons, can build up and cause brain disease. Sleep helps repair this damage and clear the debris -- essentially decluttering the brain and taking out the trash that can lead to serious illness.

Nearly all of this brain repair occurs during sleep, according to senior author Van Savage, a UCLA professor of ecology and evolutionary biology and of computational medicine, and his colleagues.

"I was shocked how huge a change this is over a short period of time, and that this switch occurs when we're so young," Savage said. "It's a transition that is analogous to when water freezes to ice."

•••••

"Sleep is as important as food," Poe said. "And it's miraculous how well sleep matches the needs of our nervous system. From jellyfish to birds to whales, everyone sleeps. While we sleep, our brains are not resting."

A chronic lack of sleep likely contributes to long-term health problems such as dementia and other cognitive disorders, diabetes, and obesity, to name a few, Poe said. When you start to feel tired, she said, don't fight it -- go to bed.

•••••