On March 13th, the 20th edition of World Sleep Day was celebrated. An annual event organized by the World Sleep Day Committee of World Sleep Society whose objective is to inform and raise awareness among the general public about the importance of sleep and the risks related to its neglect.
Under the theme Better Sleep, Better Life, Better Planet, the 20th edition was focused on the impact of the quality of our sleep on our lifestyles.
We take advantage of this event to review the existing knowledge regarding cannabinoids and their effectiveness against sleep disorders.
Sleep is one of man’s basic needs just like breathing, eating or drinking. It is essential to our health and well-being because during sleep, our body “recharges” itself. It is therefore important not to neglect this vital stage for our functioning, especially when we know that it takes up a third of our life.
Research has shown that poor sleep quality can have negative health consequences. It promotes obesity and diabetes and affects memory and learning.
Sleep studies have shown that one in three adults does not get enough sleep according to the Centers for Control and Prevention
Insomnia is the most common sleep disorder and it is said to affect nearly 30% of the American adult population, 10% of whom are chronic insomniacs… It corresponds to a longer length of time to fall asleep, difficulty in maintaining to stay asleep, a light and restless sleep and frequent awakenings at night. In the long term, the lack of quality sleep could have harmful consequences on health. In fact, 75 to 90% of insomniacs present an increased risk of co-morbid medical disorders.
The therapeutic potential of cannabis has led scientists to consider it as a possible alternative to traditional treatments for sleep disorders. Thus, since the 2000s, research on the impact of cannabinoids on sleep cycles has multiplied.
Understanding Sleep Cycles
Sleep is composed of several cycles that follow one another. A complete sleep cycle lasts from 90 to 110 minutes and consists of two main phases: NREM sleep (Non-Rapid Eye Movement Sleep) and REM sleep (Rapid Eye Movement Sleep). 
The first major phase, NREM sleep, consists of four stages:
Wakefulness sleep is the first stage of sleep. It is the transition phase between wakefulness and light sleep and lasts only a few minutes. The body prepares to fall asleep, brain activity gradually decreases and muscles relax. This is the most fragile stage of sleep and awakening is very easy.
After this first stage, the body returns to light sleep (stage 2 or N2) where awakenings are less frequent. The body continues to prepare for sleep, body temperature gradually decreases, as does brain activity and eye movements.
Then, in stages 3 and 4, which are very similar, sleep enters a deeper state, known as deep sleep. This is the most restorative part of sleep and where it is most difficult to wake up.
The last phase of sleep is REM sleep (Rapid Eye Movement or paradoxical sleep) which lasts, on average, 10 minutes during the first cycle to reach 1 hour during the last cycle. Its name comes from the paradox that occurs during this phase, where one observes signs of deep sleep (paralysis of the body) and signs of awakening (intense brain activity, rapid eye movements, irregular breathing). REM sleep is often associated with the dream phase. 
Cannabinoids and sleep disorders
Used for thousands of years for its therapeutic virtues, cannabis is a subject that fascinates the scientific community, which has multiplied research in recent years to understand how it works. Therapeutic properties have been found to relieve various pathologies such as epilepsy, pain, depression and sleep disorders.
CBD, which is non-toxic and non-addictive, is believed to be more effective in relieving anxiety than in inducing sleep. 
At low doses, THC would have a sedative effect which would lengthen the total sleep duration by reducing the time of falling asleep but also by reducing the phase of REM sleep, which, it should be remembered, plays an essential role in the consolidation of memory.
On the other hand, at high doses, THC could have hallucinogenic effects, lengthen the time to fall asleep and reduce REM sleep.  The results observed during research on the co-administration of THC and CBD differed according to the ratio of CBD:THC.
In fact, co-administration (oro-mucosal spray) of 5mg CBD/ 5mg THC and 15mg CBD/ 15mg THC would reduce deep sleep, and for the latter, an increase in wakefulness would also be observed. It seems that when taken together, CBD inhibits the sedative properties of THC.
Today, research studying the impact of medical cannabis on sleep cycles has shown that THC could be a good alternative to improve sleep, but many factors such as dosage, mode of administration and more, should be taken into account to obtain a more positive and accurate result. More research will be needed in the coming years to finally reveal the effectiveness of cannabinoids against sleep disorders.
 Memar, P., & Faradji, F. (2018). A Novel Multi-Class EEG-Based Sleep Stage Classification System. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 26(1), 84–95. doi:10.1109/tnsre.2017.2776149
 Shannon, S et alt. (2019). Cannabidiol in Anxiety and Sleep: A Large Case Series. The Permanente Journal. doi:10.7812/tpp/18-041
 Garcia, A. N., & Salloum, I. M. (2015). Polysomnographic sleep disturbances in nicotine, caffeine, alcohol, cocaine, opioid, and cannabis use: A focused review. The American Journal on Addictions, 24(7), 590–598. doi:10.1111/ajad.12291