This systematic review on illicit recreational drugs and sleep investigated the effects of cocaine, MDMA, MDE, LSD and cannabis upon subjective and objective measures of sleep, both after drug administration and during withdrawal. It also examined whether, on the other hand, sleep disturbances affect an individual’s propensity to use these drugs. The electronic databases Medline, Embase, CINAHL, PsycINFO and Psyndex were searched for all studies on these substances in conjunction with sleep, and reference lists of eligible articles were screened for further relevant studies. Articles published until October 2006 were eligible. 88 out of a total of 1200 studies were identified for analysis and twelve further studies were added when scrutinizing the reference lists. Meta-analyses were performed only for cocaine withdrawal, since number, quality and homogeneity of the other studies did not permit such analyses.
This dissertation has revealed the limitations of the available data. Studies have been flawed by a large number of methodological difficulties, some rather inevitable, some due to less rigorous standards of methodology in the past decades. It has been pointed out where future research is needed the most.
Acute administration of cocaine, MDMA and MDE increases wakefulness and suppresses REM sleep. These substances share a common pattern of acute effects on sleep with other psychostimulants such as amphetamine. LSD may have similar acute effects, but there is conflicting evidence.
In patients withdrawing from cocaine, sleep continuity measures resemble those of primary insomniacs. Even in the absence of depressed mood, REM sleep latency is not much longer than in depressed patients. After the first ten days of abstinence, sleep continuity measures deteriorate even further. Interestingly, the patients do not recognize this deterioration. It is accompanied by a worsening in cognitive performance.
Heavy ecstasy users often complain of persistent sleep disturbances. PSG studies have indicated that in abstaining heavy ecstasy users, stage 2 sleep, TST and SE are reduced. These findings can be interpreted as related to MDMA-induced serotonin neurotoxicity in humans.
Acute administration of THC increases stage 4 sleep and reduces REM sleep. After repeated administration of marijuana, tolerance develops to SWS effects. Upon withdrawal, SOL is elevated, SE is reduced and an REM rebound can be observed. Sleep disturbances constitute one of the most frequently reported symptoms of cannabis withdrawal. There is evidence suggesting that THC can be a treatment alternative for circadian rhythm disturbances, e.g. in patients with dementia and nighttime agitation.
Although some studies have shown that in patients with sleep disturbances the prevalence of drug abuse is elevated and that the incidence of new onset of an illicit drug use disorder is increased, an independent correlation or even a causal relationship has not been established. No studies have been conducted that investigated the predictive value of objective sleep disturbances during cocaine and cannabis withdrawal for treatment outcome. There are limited data on the predictive value of drug dreams during cocaine withdrawal.