Pharmacological and neurophysiological studies suggest a relationship
between brain serotonin and sleep.
In the past 10 years the study of sleep mechanisms has developed very
rapidly and has become one of the major fields of neurophysiological and
psychological research. This rapid growth is in part due to some discoveries
which have changed the classical neurophysiological picture of sleep from
the concept of a passive resting state of the brain to that of a heterogeneous
and complicated suc cession of active phenomena.
Very seldom in the history of physiology has so much effort been devoted
to the description, quantification, classification, and delimitation of
such a complex phenomenon of almost totally un known function. For this
reason, I find it unnecessary to present a detailed review of the phenomenology
of sleep and attempt instead to discuss the mechanisms involved in sleep.
I first outline the four major concepts which have changed the classical
theory of sleep. Second, I describe the neuropharmacological and histochemical
data which have made possible the link between structural data and functional
mechanisms. Finally, I present some recent findings which have led to
the belief that a complex of monoamine-containing neurons are of para
mount importance in the process under lying the succession of sleep states.