The Notion That Sleep or Wakefulness Is Regulated by a Substance

Multiple Choice

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

A) proven by the observation that naps reduce sleep time the following night.
B) unlikely, given that the cerebral hemispheres of a dolphin sleep at different times.
C) REM and slow-wave sleep appear to involve independent mechanisms.
D) proven by studies of the dolphin sleep cycle.
E) proven by studies in which blood transfusion from a tired person to a rested person results in sleep in the recipient.