A dramatic change in the purpose of sleep occurs when children are about 2 1/2 years old – a time when the main purpose of sleep changes from brain building to brain maintenance and repair, according to a study published Friday by researchers from UCLA.
“Do not wake babies during REM sleep (rapid eye movement). They do important work in their brains while they sleep, ”said Gina Poe, senior author of the study and professor of integrative biology and physiology at UCLA, which has been conducting sleep research for more than three decades.
Newborns spend about 50% of their sleep time in REM sleep, with this number falling to about 25% by age 10 and continuing to decline with age. Adults over the age of 50 spend about 1
The study, published in the journal Science Advances, notes that the abrupt shift in sleep function is “remarkable, given that this change is likely to signal a profound change in sleep function and sleep behavior.”
Researchers who used data from more than 60 sleep studies involving humans and other mammals found that all species experienced a dramatic drop in REM sleep when they reached the human development equivalent at about 2 1/2 years of age.
The transition of about 2 1/2 years corresponds to changes in brain development, according to researchers who say that sleep then helps to repair a certain amount of neurological damage suffered during waking hours and essentially dilute the brain.
“Sleep is as important as food,” Poe said. “And it’s amazing how well sleep meets the needs of our nervous system. From jellyfish to birds to whales, everyone sleeps. While we sleep, our brain does not rest. “
Poe noted that chronic sleep deprivation is likely to contribute to long-term health problems such as dementia and other cognitive disorders, and urged people to go to bed when they begin to feel tired.
Almost all brain recovery occurs during sleep, according to the study’s senior author, Van Savage, a professor of ecology and evolutionary biology and computer medicine at UCLA.
“I was shocked at how big a change this is in a short period of time and that this switch happens when we are so young,” Savage said. “It’s a transition that’s similar to when water freezes to ice.”
The study was co-authored by Junyu Cao, who conducts research in Savage’s lab and is now an assistant professor at the University of Texas at Austin; Alexander Herman, assistant professor of psychiatry at the University of Minnesota, twin cities; and Jeffrey West, a physicist who is a respected Shanan professor at the Santa Fe Institute.
The National Science Foundation and the Eugene & Claire Tau Charitable Foundation helped fund the study.