The recent legalization of cannabis for medical and recreational use in many states in the United States and internationally has resulted in a decrease in stigma and of perceived risk of cannabis use, more frequent use of cannabis, use of higher potency cannabis products, and increased dependence on cannabis use. Cannabis sativa and its derivatives are often used for improved sleep and relaxation; characteristics originally attributed to Indian hemp in the nineteenth century. Cannabis alters the sleep–wake cycle, increases the production of melatonin, and can inhibit the arousal system by activating cannabinoid type 1 (CB1 ) receptors in the basal forebrain and other wakepromoting centers. Investigations have shown that the major psychoactive compound in cannabis, ∆9 -tetrahydrocannabinol (THC), can decrease sleep onset latency in naïve users or at low doses in experienced users (eg, 70 mg/day); however, higher doses in experienced users increased sleep latency and wake after sleep onset. Indeed, frequent cannabis users (≥5 uses/week for 3 months and lifetime use ≥2 years) are reported to have shorter total sleep duration, less slow wave sleep, worse sleep efficiency, and longer sleep onset compared to controls. The contrasting benefits of THC exposure may represent the biphasic influence of THC on CB1 receptors whereby acute use causes more activation of CB1 receptors and tendency toward sleep, but long-term use results in desensitization of the CB1 receptor and decreased downstream signaling.
