The Notion That Sleep or Wakefulness Is Produced by a Substance

Multiple Choice

The notion that sleep or wakefulness is produced by a substance that circulates within the blood is

A) proven by studies of the dolphin sleep cycle.
B) unlikely given that the cerebral hemispheres of a dolphin sleep at different times.
C) unlikely because REM and slow-wave sleep appear to involve independent mechanisms.
D) proven by the observation that naps reduce sleep time the following night.
E) unlikely given that blood chemistry does not change within the brain.