Drugs affecting sleep and wakefulness: a review

Abstract

It was in the second half of the twentieth century that Sleep Medicine was recognized as an immensely respected field of clinical research. As a result, past few decades have seen this field making some giant strides towards a better understanding of the neurochemical mechanisms that regulate the state of sleep and wakefulness. This involves a complex interplay of neuronal systems, neurotransmitters and some special nuclei located in the brain. Major wakefulness promoting nuclei being the orexinergic neurons in the lateral hypothalamic region and the tuberomammillary nucleus (TMN) while the sleep-promoting nucleus being ventrolateral preoptic nucleus (VLPO). Sleep-related complaints are one of the common complaints encountered by the physicians and the psychiatrists. As, long-standing sleep disturbances can have far-reaching implications on an individual’s physical, mental and social wellbeing, the importance of drugs affecting sleep and wakefulness could not be stressed upon anymore. Broadly, the sleep disorders are classified as insomnia, hypersomnia, and parasomnia and the presently available drugs work either by acting on the sleep-promoting GABAergic system like benzodiazepines, barbiturates etc. or by interacting with wakefulness promoting system like histaminergic system, 5- hydroxtryptaminergic system, orexinergic system etc. There are drugs which interact with other mechanisms which modulate arousal, like melatonin receptor agonists which promote sleep and adenosine receptor antagonists which promote wakefulness. This review article tries to have an overview of the available drugs for use in pathological states of sleep and wakefulness with a special emphasis on the commonly prescribed drugs and the recently approved one’s.