ABSTRACT
This chapter is based on these differences in the level of brain arousal that characterize sleep and wakefulness. An understanding of the relevant neurophysiology and neurochemistry has emerged gradually during more than 50 years of research. With that as background, we will focus on the principal neurochemical pathways and receptors that influence these changes as wakefulness proceeds to sleep and vice versa. The reader will find it convenient to consider wakefulness as a state of brain activation that results from the influence of certain excitatory neurotransmitters, NREM sleep as the gradual reduction of that excitatory drive, and then REM sleep
as a rather different aroused state, but one that is still modulated by some of the same excitatory pathways that are active during wakefulness. Similarities between wakefulness and REM sleep will be apparent in terms of the neurotransmitters and receptors involved in the generation of the two states and the mechanisms of cortical activation. This chapter should not be considered exhaustive, because we emphasize the neurochemistry that is the basis for current treatment options in the sleep clinic. There are also, probably, neurotransmitter pathways waiting to be discovered, especially in the control of the transition between the various vigilance states.
