Page "Rapid eye movement sleep" Paragraph 9

According to another theory, known as the Ontogenetic Hypothesis of REM sleep, this sleep stage ( also known as active sleep in neonates ) is particularly important to the developing brain, possibly because it provides the neural stimulation that newborns need to form mature neural connections and for proper nervous system development.

Studies investigating the effects of active sleep deprivation have shown that deprivation early in life can result in behavioral problems, permanent sleep disruption, decreased brain mass, and result in an abnormal amount of neuronal cell death.

Further supporting this theory is the fact that the amount of REM sleep in humans decreases with age, as well as data from other species ( see below ).