How Does Cannabis Affect Sleep?

Date Published: 06 Nov 2018 Categories: News
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Cannabis and Sleep

The use of cannabis has become an increasingly popular topic of discussion following global policy changes and in more recent times, the decriminalization of cannabis for personal use in South Africa. Research on how cannabis affects sleep started as far back as the 1970s, with a resurgence in interest toward the mid-2010s. Up until now, our understanding of cannabis has become even better understood following advances in medical research. Despite relaxed laws on this once banned drug, it is important to know the facts regarding the potential risks and benefits of cannabis use on sleep.


Cannabis and cannabinoids

 Cannabis the drug (also known as marijuana, among many other names) refers to the psychoactive agent of the cannabis plant. Cannabis may be derived from different source plants, including the sativa and indica species, and is broadly used for medical and recreational purposes. Cannabinoids are the active compounds found within the cannabis plant. These compounds work by actively binding and interacting with special sites in the brain and nervous system. While there are over 100 different types of cannabinoids in existence, there are two cannabinoids that are of significant interest: THC (delta-9 tetrahydrocannabinol) and CBD (cannabidiol).

Although THC and CBD are both the most commonly studied cannabinoids, they are quite different. THC is the primary psychoactive component of cannabis, better known for its “high” inducing properties, while CBD is the non-intoxicating component of cannabis. The effect of THC varies largely with dose; however, CBD may modulate THC by counteracting its effect. CBD has been a focal point in medicinal cannabis research, particularly for its therapeutic potential. CBD oil, for example, has been proposed as a treatment option for chronic pain management, anxiety disorders and even certain cancers.


How does cannabis influence sleep?

Many of the studies looking at how cannabis influences sleep has come with mixed results. On the one hand, cannabis may have a short-term benefit by reducing the time it takes to fall asleep, increasing sleep duration and increasing the time spent in deep (slow-wave) sleep – the part of sleep which is important for mental recovery and memory consolidation. On the other hand, cannabis seems to reduce the amount of rapid eye movement (REM) sleep, the part of sleep which is linked to dreaming, learning and forming new memories.

Interestingly, CBD and THC have differential effects on sleep which may explain some of the many discrepant research findings. For example, THC has sleep promoting effects, however, the effects of CBD on sleep vary with dose. Low-dose CBD has a stimulating effect and is associated with an increased feeling of wakefulness, whilst high-dose CBD has a sedating effect.

Taken together, it is possible that short-term cannabis use may have some benefit on sleep, especially by making it easier to fall asleep and by helping to get more deep sleep.

Long-term cannabis use, however, seems to impact sleep negatively. For example, individuals may find themselves stuck in a vicious cycle of using cannabis to manage their sleep because they may habituate to the effects, meaning with repeated use, they will need higher doses of cannabis to achieve the same desired effect. This may lead to problematic cannabis use, which may increase the risk for cannabis dependence. Sleep disturbances are also a hallmark trait of cannabis withdrawal, meaning that if a cannabis user decides to quit, they may experience worsened sleep that may predict a relapse.

Individuals who suffer with problematic sleep as a result of chronic pain may benefit from using cannabis for pain management. With that said, it is imperative to balance the potential risks and benefits of such therapy with strict monitoring by a trained medical professional.


So, should I use cannabis for sleep?

The type of cannabinoids, their ratios, dosage, timing and route of administration (not discussed here) all play a critical role in their respective outcomes. Moreover, while cannabis remains unregulated, it is simply not possible to know for certain what the constituent ratio and dosage of cannabinoids are in any given cannabis sample. Beyond this, it’s difficult to discern between short- and long-term use, given the abundance of mixed study results and variable tolerance to its use among different people.

Research on cannabis and sleep remains in its infancy and requires further research in controlled settings. It is without a doubt an exciting development that shows potential, however, if you are considering cannabis to manage your sleep, or you are struggling with cannabis use then we urge you to seek the guidance of a medical doctor. With that said – we do not advocate the use of cannabis for sleep.


Chadley Kemp, BSc(Med)(Hons)

Sleep Scientist | Sleep Science | Sports Science Institute of South Africa

MSc candidate | Health through Physical Activity, Lifestyle and Sport Research Centre | Faculty of Health Sciences | University of Cape Town

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