numerous medical conditions (e.g., type-II diabetes, Attention-Deficit/Hyperactivity
Disorder, depression) and other biological phenomena (e.g., exercise, infant sleep, sleep
deprivation) will have to be worked out thoroughly in the future. For the present, it only
needs to be noted that this theory is testable. It should not be difficult to make an
exhaustive comparison of the physiological features associated with tonic REM sleep,
phasic REM sleep, effort, and arousal in human beings. The technology needed to
monitor cerebral metabolism is now available, and it is also being rapidly improved.
I predict that two central tenets of this theory will withstand all future scrutiny.
First, REM sleep involves the replenishment of a depleted ATP reserve somewhere in the
brain. Present evidence suggests that the hippocampus is mostly likely the part of the
brain that is re-energized during REM sleep. However, there are several other areas of the
brain that may also be re-energized during this stage of the sleep cycle. Second, glucose
is transferred from the body to the brain via the bloodstream during phasic REM sleep
and during increases in physiological arousal that occur while a person is awake.
Many questions about sleep still remain to be answered, but it now seems clear
that the primary function of REM sleep is to re-energize the brain.
6. References
Abrahams, V. C., & Hilton, S. M. (1964). The Role of Active Muscle Vasodilatation in
the Alerting Stage of the Defence Reaction. J Physiol, 171, 189-202.
Anchors, J. M., & Burrows, B. L. (1983). Changes in brain glycogen during slow-wave
sleep in the rat. J Neurochem, 41(5), 1498-1501.
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preliminary draft (9/24/2006)