Substance-Related Sleep Disorders

The consumption of a wide variety of substances determines, through different mechanisms, the onset of sleep disturbances, which has a considerable impact on the neurobiology of sleep-wake circadian rhythm. Many substances are widely used and easy to find, such as alcohol, nicotine and caffeine and are frequently the cause of degradation in quality and quantity of sleep. Furthermore, substance abuse is often associated with poor sleep hygiene. In this case, the regularity of sleep-wake cycle is affected not only by the direct effect of the substances, but also by the presence of correlated disturbing factors in the sleep environment that do not support the synchronization of circadian cycle [1]. Even illicit substances, both psychostimulants and inhibitors of central nervous system such as heroin, cocaine and ecstasy have mechanisms of action that lead to a high potential for dysregulation of sleep. The current literature describes sleep abnormalities related to the use/abuse of many other substances sold on the street market or on the internet: cannabis, hallucinogens, methamphetamine, novel psychoactive drugs, etc. In a considerable number of cases, sleep disturbances are caused by prescribed substances such as corticosteroids, beta-blockers, benzodiazepines and hypnotics, antidepressants, chemotherapy, etc. which can adversely affect sleep through several different mechanisms. In particular, a significant impact on the above phenomenon is represented by the long-term use of sedative-hypnotics compounds, mainly benzodiazepines, that may generate a dysregulation of sleep through the onset of dependence patterns [2]. From 3-7% of all sleep disorders are caused by use/abuse of psychotropic substances, and 12-16% do have not an apparent cause. It is possible to hypothesize that a variable percentage of these cases could be drug-related cases, underestimated for various reasons. Furthermore, sleep disturbances and substance use correlate with an increased prevalence of psychiatric disorders. It has been reported that 51% of patients with psychiatric disorders become addicted to at least one substance, and E-mail: [email protected]. Complimentary Contributor Copy Alessandro E. Vento and Paolo Girardi 232 41-66% of individuals with substance dependence/addiction have a psychiatric disorder. Mental disorders are the main cause of sleep disturbances (e.g. psychiatric illness represents about 30-40% of all cases of insomnia). This fact emphasizes the strong correlation between psychopathology, use/abuse of substances and sleep disorders [3, 4, 5]. The discussion of the molecular and neurobiological mechanisms that bring into connection the use/abuse of substances with qualitative and quantitative alterations of sleep is the central focus of this chapter.