ABSTRACT
Chemical involvement in sleep and waking is, of course, apparent in the neurochemicals that are involved in the neural mechanisms. This chapter discusses mechanisms based on noradrenaline, acetylcholine and serotonin earlier. Another sleep-promoting substance is the inhibitory neuromodulator adenosine. It was noticed in the late 1950s and early 1960s that anesthetizing a region in the brain stem, between the pons and the medulla of a sleeping cat causes it to wake up. At about the same time evidence began to gather that the features of rapid eye movement (REM) sleep could be separately affected by manipulations such as localized lesions and REM sleep deprivation. Direct projections to the thalamus control cortical arousal, and hence the desynchronized electroencephalogram, while those to the lateral geniculate nucleus of the thalamus produce PGO waves, and those to the tectum produce rapid eye movements.
