Cannabis, Cannabinoids, and Sleep : a Review of the Literature
Kimberly A. Babson, James Sottile, Danielle Morabito
Current Psychiatry Reports, 2017, 19, 23
Doi : 10.1007/s11920-017-0775-9
Purpose of Review : The current review aims to summarize the state of research on cannabis and sleep up to 2014 and to review in detail the literature on cannabis and specific sleep disorders from 2014 to the time of publication.
Recent Findings : Preliminary research into cannabis and insomnia suggests that cannabidiol (CBD) may have therapeutic potential for the treatment of insomnia. Delta-9 tetrahydrocannabinol (THC) may decrease sleep latency but could impair sleep quality long-term. Novel studies investigating cannabinoids and obstructive sleep apnea suggest that synthetic cannabinoids such as nabilone and dronabinol may have shortterm benefit for sleep apnea due to their modulatory effects on serotonin-mediated apneas. CBD may hold promise for REM sleep behavior disorder and excessive daytime sleepiness, while nabilone may reduce nightmares associated with PTSD and may improve sleep among patients with chronic pain. Summary Research on cannabis and sleep is in its infancy and has yielded mixed results. Additional controlled and longitudinal research is critical to advance our understanding of research and clinical implications.
Keywords : Cannabis . Cannabinoids . Sleep . Insomnia . Sleep apnea
Rates of cannabis use within the USA continue to increase, with 8.3% of the US population reporting cannabis use within the past month . Cannabis use has been associated with the development of cannabis use disorders, particularly among “at-risk” populations. In contrast, there has also been evidence to suggest that cannabis may have therapeutic potential. Indeed, as of January 1, 2017, 26 states and the District of Columbia have legalized cannabis for medical purposes, while 7 states and the District of Columbia have legalized the recreational use of cannabis. Understanding the research on both sides of this coin is important for clinical, research, and policy purposes.
The current paper seeks to provide a state-of-the-science review of the research on cannabis and sleep, a condition for which individuals often report using cannabis . Previous review papers have provided an overview of the research on cannabis and sleep up through 2014. Therefore, within this review, we will provide a summary of the hallmark work in this area through 2014 along with an update of new research
from 2014 to the end of 2016. First, we will provide a primer on cannabis and cannabinoids and how they relate to sleep. We will then provide an overview of research on both sides of this topic, namely, the risk and potential benefits of cannabis on sleep and the impact of poor sleep on cannabis use. Finally, we will provide an overview of the research on cannabis and specific sleep disorders. We will conclude with an integrative summary and call for future directions.
Introduction to Cannabinoids
The cannabis flower is comprised of over 100 different cannabinoids, the active compounds found within the cannabis plant. Cannabinoids work on the endocannabinoid system (ECS) which consists of a series of neuromodulatory lipids and receptors located throughout the brain and central and peripheral nervous system, which accept endogenous cannabinoids (anandamide, 2-arachidonoylglycerol) and phytocannabinoids (plant-based). The CB1 and CB2 receptors are two main receptors within the ECS . The two most wellresearched phytocannabinoids are delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the primary psychoactive component of cannabis which is responsible for the “high” associated with cannabis use. THC acts on CB1 receptors and yields a biphasic effect such that the impact of THC varies between low and high doses. CBD is a non-intoxicating constituent of cannabis which acts on CB2 receptors. CBD has been shown to counter the effects of THC and has received
a lot of attention for its potential therapeutic effects .
Based on the potential therapeutic impact, cannabis-based medicine extracts have been developed. These extracts are synthetic THC (dronabinol, nabilone), CBD (Charlotte’s web), and nabiximols (1:1 CBD/THC, Sativex) which are delivered orally. The development of synthetic extracts has allowed for investigation of the effects of specific cannabinoids.
The Impact of Cannabis on Sleep
Research on the impact of cannabis on sleep started in the 1970s and included a number of studies examining polysomnography (PSG)-based sleep. This resulted in mixed findings with some work showing a decrease in sleep onset latency  and wake after sleep onset , while other work did not replicate these findings , but instead observed an increase in slow wave sleep [7, 8] and a decrease in REM [6, 7, 9]. Additional work from this era also suggested that cannabis may have a short-term benefit on sleep, particularly in reducing sleep onset latency ; however, chronic use of cannabis could be associated with habituation to the sleep inducing and slow wave sleep-enhancing properties [8, 11–13].
This initial work suggested that long-term use could have a negative impact on sleep in two primary ways. First, individuals may find themselves in a vicious cycle of using cannabis to manage sleep, habituating to the effects, and using more cannabis in order to obtain the desired impact, resulting in problematic patterns of use. Second, sleep disturbances are the hallmark of cannabis withdrawal and may serve to maintain use and predict relapse.
Sleep and Cannabis Relapse
A breadth of evidence has converged to demonstrate that poor sleep is a critical risk factor for predicting cannabis cessation success [14–16]. Poor sleep quality prior to a quit attempt has been shown to increase the risk of early lapse/relapse to cannabis  and be associated with less of a reduction in cannabis use frequency among cannabis-dependent veterans . Post-quit sleep has also been shown to impact quit success and rates of lapse/relapse to use [14, 17–19]. For example, Budney and colleagues  demonstrated that 65% of cannabis users reported poor sleep as the primary reason for lapse/relapse to cannabis during a prior quit attempt.