UCLA-led research team finds REM sleep first builds, then maintains human brains

A University of California, Las Angeles (UCLA)-led team of scientists has been able to show that sleep takes on a significantly different function in the human brain around the age of 2.5 years, and Rapid Eye Movement (REM) sleep in that first stage is essential to brain development.

Up until around 2.5 years old, the human brain is growing rapidly, according to a UCLA press release. REM sleep is when synapsis are being created and strengthened.

“Don’t wake babies up during REM sleep — important work is being done in their brains as they sleep,” Gina Poe, senior study author, was quoted as saying in the release.

Poe is a UCLA professor of integrative biology and physiology who has conducted sleep research for more than 30 years, according to the release.

But once humans pass that building stage, REM sleep becomes an opportunity for the brain to repair and maintain itself, according to the release. 

Any animal brain takes on damage during periods when it is awake, according to the release. The result is debris in the form of damaged genes and proteins lying around in neurons.

If the debris were permitted to build up, the result would be brain disease, according to the release. 

“Sleep helps repair this damage and clear the debris – essentially decluttering the brain and taking out the trash that can lead to serious illness,” the release states.

Almost the entirety of brain maintenance requires humans to be asleep, according to the release.

But building the brain to start with takes even more sleep, and the research team – which included scientists with expertise in neuroscience, biology, statistics and physics – found through 60 sleep studies of humans and other mammals that all species had a REM sleep decrease significantly around the same point in development, according to the release.