Neural activity reveals continuity between infant and adult sleep


Infant sleep: A precursor to adult sleep?

Though naked, helpless, and blind, this week-old rat (pictured with a quarter) already has the fundamental neural components of adult sleep. (Photo: Mark Blumberg)
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Sleep is absolutely essential for well-being. Just ask one of the 40 million Americans with sleep disorders who suffer crippling fatigue, impaired judgment, irritability, moodiness, and myriad health problems. Still, its precise function remains unclear. An intriguing role for REM sleep - the stage most closely associated with dreaming - was suggested almost 40 years ago when sleep researchers Howard Roffwarg and William Dement discovered that babies spend far more time in REM sleep than adults - prompting their hypothesis that infant REM sleep plays a role in central nervous system development. A central element of their hypothesis is built on whether the neural mechanisms of infant sleep differ significantly from those of adult sleep, but they relied on untested assumptions on the nature of infant sleep.

In a new study published in the open-access online journal PLoS Biology, Karl Karlsson, Mark Blumberg, and their colleagues tackle the technical difficulties involved in studying the tiny neonatal brain to investigate the neural activity associated with infant sleep states. Using techniques ranging from neural recording, anatomical tracing, and microlesioning, they provide evidence that the active sleep of week-old rats bears a striking resemblance to the conventional definitions of adult sleep. What's more, the neural mechanisms underlying the infant sleep state contain the primary components of adult sleep.

Altogether, the authors argue, these results show that sleep development elaborates on elementary components already in place soon after birth. If the neural mechanisms of infant and adult sleep were entirely different, then sleep might serve different purposes in infancy and adulthood. But the striking parallels outlined in this study suggest a developmental continuity between the two states. They also chart a course for future study that might even test Roffwarg's view that the neonatal brainstem primes the central nervous system for the sensory challenges that lie ahead - and could even be the stuff that dreams are made of.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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