Hypnogenic center theory of sleep: no support from metabolic mapping in monkeys.

By comparing rates of glucose utilization in brains of monkeys in non-REM sleep and two types of awake controls, we attempted to reveal cerebral hypnogenic centers that drive organisms to sleep through increases in their neural activity. Instead we found that metabolic activity is reduced in all the putative hypnogenic centers during sleep as compared to wakefulness. The results thus offer no support for the notion of an active center that either maintains or triggers sleep.