Serotonin (5-hydroxytryptamine [5-HT]) is one of the oldest biologically active compounds on earth, preserved through at least 500 million years of evolution. Since its discovery in the 1940s in the mammalian intestinal mucosa and in the central nervous system, 5-HT has been shown to be involved in virtually all cognitive and behavioral human functions, and alterations in its neurochemistry have been implicated in the etiology of a plethora of neuropsychiatric disorders, such as schizophrenia, depression, anxiety, and Parkinson disease. Since the beginning, it appeared that 5-HT might have a role in sleep, but initial enthusiasm has been dampened because of the subtle effect demonstrated by this monoamine. Today, the interest in 5-HT in sleep research is going through a renaissance, thanks to the availability of highly selective serotonergic compounds and the urgent need for new sleep disorder treatments owing to the shortcomings of current ones. Notably, more than one-quarter of the US population report receiving insufficient sleep; 10% report having sleep disorders.1 The market for pharmaceutical companies developing new drug treatments for these disorders is potentially worth billions of dollars. The serotonergic system and in particular the 5-HT2 receptor subtypes have recently emerged as among the most promising targets in the search for effective and well-tolerated novel medications for treating primary and secondary sleep disorders.
Di Giovanni G. Serotonin and Sleep: Molecular, Functional and Clinical Aspects. JAMA. 2009;302(18):2036-2037. doi:10.1001/jama.2009.1648