An introduction to insomnia

Insomnia is a common sleep disorder that affects millions of people around the world, including around 31% of adults in the UK. While adults usually require at least 6-9 hours of sleep every night to function properly in daily life, people with insomnia struggle to get enough sleep.

There are many possible causes of insomnia, but the most common are environmental factors and psychological or physiological stress. It can be difficult to fall asleep if you’re in a new place, an uncomfortable bed, or somewhere with excessive noise, light, or temperatures. Similarly, medical conditions whose symptoms cause discomfort and pain can keep you awake, as can anxiety about work, school, relationships, or even your health.

Transient insomnia can pass within a week, and acute insomnia usually passes within one month as you resolve or adapt to the stressor. However, insomnia can become a chronic condition if the underlying causes cannot be resolved. Chronic insomnia can have a severe impact on your health and quality of life if you’re constantly experiencing sleep deprivation.

What happens when you have insomnia?

Insomnia involves having difficulties falling asleep and/or staying asleep. Even if you are able to get to sleep, you might find yourself waking up often and taking a long time to fall asleep again. This will leave you feeling tired and irritable throughout the day, making it difficult for you to concentrate.

This increases the risk of accidents and injuries, especially if you have to drive. Continuous sleepless nights won’t just cause ‘brain fog’ and low mood, either – there are many physical and mental consequences for lack of sleep. When your body and mind are unable to repair themselves during sleep for a long period of time, this also increases the risk of:

  • Hypertension (high blood pressure)
  • Heart disease
  • Weight gain and obesity
  • Type 2 diabetes
  • Weakened immune system
  • Loss of libido (sex drive)
  • Decreased fertility
  • Depression and anxiety

With so much at stake for people struggling with the mounting sleep debt caused by insomnia, many people are interested in alternative therapies to treat the condition, such as cannabis. That said, there’s still a long way to go before medical marijuana for insomnia can become commonplace.

Medical cannabis and insomnia: what does the evidence say?

Cannabinoids, the naturally occurring chemical compounds found in marijuana, can vary in concentration and effect. The two most researched types are CBD (cannabidiol) and THC (tetrahydrocannabinol), the latter of which is psychoactive and can cause a ‘high’.

There’s a lot of anecdotal evidence about marijuana causing either elevated mood or drowsiness, which depends upon the particular strain. Theoretically, medicinal cannabis could help an insomniac to relax, fall asleep, and stay asleep more easily. This could also help the individual to stay awake and alert throughout the day, and maintain a better mood.

The majority of scientific research into medicinal cannabis has largely been concerned with pain reduction, with the effects of cannabinoids on disordered sleep being ancillary. However, research into the potential use of cannabis for insomnia and related sleep disorders has been growing in recent years. Here are several examples supporting the use of cannabinoids to relieve insomnia:

  • 2007 – A review of studies on the therapeutic effects of cannabis-based medicine (Sativex) reported a ‘marked improvement in subjective sleep parameters’ for patients with chronic pain conditions, with up to half of the subjects experiencing good quality sleep for up to 4 years without developing a tolerance or requiring a higher dosage.1
  • 2008 – A study on the effects of recreational drugs on sleep found that ‘acute administration of cannabis appears to facilitate falling asleep and to increase Stage 4 sleep’ (REM or Rapid Eye Movement sleep, when dreams occur), while THC specifically reduces REM sleep. THC could therefore be useful where sleep disturbances are caused by nightmares and PTSD.2
  • 2010 – A randomised trial with chronic pain patients found that inhaling 25mg of cannabis (9.4% THC) 3 times a day for 5 days reduced pain intensity and improved sleep compared to a placebo (patients reported falling asleep faster and experiencing a better quality of sleep).3
  • 2012 – A review of research into the therapeutic targets of CBD concluded that a daily dose of 150-600mg of oral CBD could alleviate symptoms of conditions including but not limited to insomnia, anxiety, and epilepsy.4
  • 2017 – A literature review of research on cannabinoids and sleep found that different types are promising for treating different sleep disorders such as REM Sleep Behaviour Disorder (physically acting out dreams). It also suggests synthetic cannabinoids to treat sleep apnoea and PTSD, without the long-term issues associated with THC.5
  • 2017 – While routine changes such as switching between day and night shifts can disturb sleep, a study simulating such shifts found that workers slept longer, felt less tired and sad, and performed vigilance tasks better after smoking low-THC marijuana cigarettes compared to placebos.6
  • 2018 – A study by the University of Mexico gathered data from the Releaf app (for tracking cannabis use) and found that ‘consumption of cannabis flower is associated with significant improvements in perceived insomnia’, reporting a reduction of symptom severity of 4.5 points on a 0-10 scale, with a greater reduction in symptoms for high CBD strains than THC.7
  • 2019 – A study on the clinical application of CBD for sleep and anxiety problems found that sleep scores improved in 66.7% of patients, though they fluctuated over time. Anxiety scores decreased in 79.2% of patients, and 95% tolerated the CBD well. Reference is also made to CBD appearing to decrease levels of the stress hormone cortisol due to its sedative effects.8
  • 2020 – A cross-sectional study on adults over 50 with chronic pain and insomnia found that those who used medical cannabis experienced fewer problems with waking up at night than those who didn’t. However, tolerance developing from frequent use can reduce its sleep-inducing properties.9
  • 2021 – A cross-over placebo-controlled trial on chronic insomnia patients found that cannabinoid extract reduced insomnia severity, decreasing sleep onset latency and waking after sleep onset, while increasing total sleep time and feelings of being rested on waking. The cannabinoid was well-tolerated with no serious adverse effects.10

These studies and reviews from the past 14 years indicate that cannabis can indeed aid with sleep, and therefore reduce the severity of sleep disorders such as insomnia. CBD for insomnia seems to be only effective in combination with THC. Its therapeutic effects appear to be most promising where insomnia is comorbid with, or caused by, another condition – such as chronic pain, anxiety, or PTSD.

The research also indicates that the symptom-relieving effects are dependent upon the condition and the cannabinoid type and dosage, and that more clinical studies are required to identify the most appropriate cannabis treatment for specific disorders.

Insomnia and the endocannabinoid system

To understand how cannabis affects the body and works to reduce the symptoms of insomnia, we must consider the endocannabinoid system (ECS). This is a physiological system in the human body made up of cannabinoid receptors and endocannabinoids (naturally produced cannabinoids). Phytocannabinoids (which occur in the cannabis plant, including CBD and THC) can interact with the ECS in a similar way to endocannabinoids.

Cannabinoid Type 1 (CB1) receptors are mainly part of the central nervous system (CNS), while Cannabinoid Type 2 (CB2) receptors are part of the immune system.11 CBD can affect CB2 receptors to relieve pain and inflammation, while THC can attach to CB1 receptors and influence neurological signals more strongly, including relaxation, appetite, and mood.12

Cannabis, more specifically THC, is known to activate CB1 receptors and inhibit the body’s arousal system, altering the sleep-wake cycle and initially inducing drowsiness – though higher doses and frequent use can eventually cause the opposite effect.13 The sleep-wake cycle usually goes like this:

  • Stage 1: Awake – When you are fully conscious before falling asleep.
  • Stage 2: Light Sleep – Transitioning into deeper sleep; your muscles relax and your breathing and heart rate slow down.
  • Stage 3: Deep Sleep – Physically restorative sleep; your body works on cell and hormone repair and flushing out waste.
  • Stage 4: REM Sleep – Mentally restorative sleep; the brain becomes more active, triggering dreams and memory retention.

You will cycle through these stages several times a night, not necessarily in order, spending up to 20% of the time in REM sleep and the rest of the time in non-REM sleep. If cannabinoids can suppress the arousal system, and encourage the production of sleep-promoting adenosine, this can result in sedation.14 This makes it much easier for the body to enter Stage 2, and stay asleep for long enough to experience uninterrupted periods of deep sleep and REM sleep at Stages 3 and 4.

As mentioned earlier, when anxious thoughts and feelings and PTSD are the cause of sleep problems, THC can limit REM sleep and reduce the possibility of dreams or nightmares. However, the body and mind still require REM sleep to function healthily, so patients must not suppress this sleep stage excessively.

Since there is some concern regarding a dependency or tolerance developing for THC that could cause the return or worsening of insomnia symptoms, it’s worth looking into other cannabinoids such as CBN (cannabinol) – an aged and oxidised form of THC that has stronger sedative effects when used with lower amounts of THC, but is only mildly psychoactive.15 More research is needed into the use of this specific derivative, or other cannabis compounds and combinations.

How does cannabis compare to current treatments for insomnia?

There are many different sleep disorders with a variety of possible treatments, which are usually selected on a case-by-case basis to target the apparent cause. In mild cases, alleviating insomnia can be as simple as cutting back on caffeine and going to bed at a regular time. Here are some of the most common treatments for insomnia:

  • Sleep hygiene – creating a regular routine with set sleeping and waking times, sleeping in a dark, quiet, and comfortable place, avoiding oversleeping
  • Lifestyle changes – avoiding daytime naps, relaxing before bed without eating, exercising, watching TV, or using devices like smartphones in the hours before going to sleep
  • Therapy – learning relaxation techniques or stimulus control, cognitive restructuring with CBT (Cognitive Behavioural Therapy)
  • Medication – pharmaceutical sleeping aids (e.g. antihistamines or melatonin), or stronger sleeping pills prescribed by a doctor

If adjusting your habits doesn’t improve your insomnia, you might try medications, but these are only recommended as a temporary solution. When psychoactive properties are limited, cannabis is believed to be much safer than conventional sleeping aids, since prescription sleeping pills tend to have unpleasant side effects and a higher risk of addiction.7 Patients in studies have expressed a preference for cannabis to improve sleep and reduce pain without over-relying on medication.13

Medical cannabis is not only useful for insomnia relief, but also in treating a range of psychiatric and physiological conditions whereby insomnia is a secondary symptom.4 Of course, the effects depend on the cannabinoid concentration and dosage, which must be clinically assessed by an expert. At present, professionals on the General Medical Council’s Specialist Register can legally prescribe cannabis products for medicinal purposes.

However, regulations currently limit the use of medical marijuana in the UK for the relief of chronic pain, so you may only be able to access marijuana for insomnia if it is comorbid with chronic pain. Find out whether you would be eligible for cannabis treatments for your insomnia by booking a consultation with the experts at Cannabis Access Clinics (you can click here for more information about this process).


1) Russo EB, Guy GW, Robson PJ. (2007). ‘Cannabis, pain, and sleep: lessons from therapeutic clinical trials of Sativex, a cannabis-based medicine. Chemistry & Biodiversity, 4(8), pp. 1729-1743.

2) Schierenbeck T, Riemann D, Berger M, Hornyak M. (2008) ‘Effect of illicit recreational drugs upon sleep: cocaine, ecstasy and marijuana’. Sleep Medicine Reviews, 12(5), pp. 381-389.

3) Ware MA, Wang T, Shapiro S, Robinson A, Ducruet T, Huynh T, Gamsa A, Bennett GJ, Collet JP. (2010). ‘Smoked cannabis for chronic neuropathic pain: a randomized controlled trial’. Canadian Medical Association Journal, 182(14), pp. 694-701.

4) Zhornitsky S, Potvin S. (2012) ‘Cannabidiol in humans-the quest for therapeutic targets’. Pharmaceuticals (Basel), 5(5), pp. 529-552.

5) Babson KA, Sottile J, Morabito D. (2017). ‘Cannabis, Cannabinoids, and Sleep: a Review of the Literature’. Current Psychiatry Reports, 19(4), p. 23.

6) Keith DR, Gunderson EW, Haney M, Foltin RW, Hart CL. (2017) ‘Smoked marijuana attenuates performance and mood disruptions during simulated night shift work’. Drug and Alcohol Dependence, 178, pp. 534-543.

7) Vigil JM, Stith SS, Diviant JP, Brockelman F, Keeling K, Hall B. (2018) ‘Effectiveness of Raw, Natural Medical Cannabis Flower for Treating Insomnia under Naturalistic Conditions’. Medicines (Basel), 5(3), p. 75.

8) Shannon S, Lewis N, Lee H, Hughes S. (2019) ‘Cannabidiol in Anxiety and Sleep: A Large Case Series’. The Permanente Journal, 23, pp. 18-41.

9) Sznitman SR, Vulfsons S, Meiri D, Weinstein G. (2020) ‘Medical cannabis and insomnia in older adults with chronic pain: a cross-sectional study’. BMJ Supportive & Palliative Care, 10(4), pp. 415-420.

10) Walsh JH, Maddison KJ, Rankin T, Murray K, McArdle N, Ree MJ, Hillman DR, Eastwood PR. (2021). ‘Treating Insomnia Symptoms with Medicinal Cannabis: A Randomized, Cross-Over Trial of the Efficacy of a Cannabinoid Medicine Compared with Placebo’. Sleep, zsab149.

11) Rahn EJ, Hohmann AG. (2009). ‘Cannabinoids as pharmacotherapies for neuropathic pain: from the bench to the bedside’. Neurotherapeutics, 6(4), pp. 713–737.

12) Pertwee RG. (2008) ‘The diverse CB1 and CB2 receptor pharmacology of three plant cannabinoids: delta9-tetrahydrocannabinol, cannabidiol and delta9-tetrahydrocannabivarin’. British Journal of Pharmacology, 153(2), pp. 199-215.

13) Bowles NP, Herzig MX, Shea SA. (2017). ‘Recent legalization of cannabis use: effects on sleep, health, and workplace safety’. Nature and Science of Sleep, 9, pp. 249-251.

14) Babson KA, Bonn-Miller MO. (2014). ‘Sleep Disturbances: Implications for Cannabis Use, Cannabis Use Cessation, and Cannabis Use Treatment’. Current Addiction Reports, 1, pp. 109–114.

15) Russo, EB. (2011). ‘Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects’. British Journal of Pharmacology, 163, pp. 1344-1364.

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