While adults spend less than a quarter of their sleep time engaged in dreaming (or REM sleep), young babies engage in REM sleep for over 50% of their total sleep time. So why do babies dream more than adults? Why should infants dream so much when they have far less activities during the day that might trigger dreams?
One theory claims that REM sleep provides young babies with the mental stimulation their growing brains need. The phenomenon has been equated to activities such as kicking in the womb, whereby the fetus “practices” kicking and walking actions in preparation for later locomotor activities after birth.
Similarly, REM sleep in babies is believed to stimulate the nerve pathways that will be used at a later date to process the world outside. This would explain why the ratio of REM sleep to non-REM sleep decreases as babies mature. As they grow older, babies and infants are able to gain increasing levels of mental stimulation from the world around them, and have less need for the self-stimulation of REM sleep.
Researchers have studied babies who have been deprived of REM sleep (due to factors such as illness, or the pain of circumcision) whereby normal sleeping patterns are disrupted. In adults with sleep deprivation, the total REM sleep phases increase as the person readjusts back to their normal sleep pattern. It is just the opposite with babies. Where REM sleep is interrupted and the baby is sleep deprived for any of the above reasons, it is non-REM sleep which increases during the “catch-up” process. This makes sense if the function of REM sleep in babies, unlike the adult, is mental stimulation. It is believed that the experience of stressful incidences such as pain and illness reduced the infant’s need for REM sleep, because the stressful event in itself provides the baby with a source of mental stimulation.
Premature babies also spend longer periods in REM sleep than do their full-term counterparts. As the brain of a premature baby is less developed, the increased need for REM sleep supports the self-stimulation theory since premature babies are in greater need of neuronal stimulation than full-term neonates.
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