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Marijuana and sleep: does it help or harm?

The relationship between cannabis and sleep is complex. Online forums indicate that many view cannabis as an easy DIY sleep aid, while others claim that cannabis disrupts their sleep and negatively affects their ability to wake up in the mornings. According to the research available, both views could potentially be correct based on various factors including: the type of cannabinoid being used (THC or CBD), the frequency of use, the dosage of the product or its potency, and the user’s reason for sleeping poorly (insomnia, stress, pain, etc.).

Below is the information from the scientific literature regarding the relationship between cannabis and sleep — without all the hype.

1) Cannabis can appear to improve sleep

Short-term use of THC can produce a sedative effect for some individuals and CBD can be anxiolytic for some users. Therefore, when sleep difficulties are caused by anxiety or physical discomfort, this relief can sometimes seem like a marked improvement in sleep.

Many users report:

  • faster falling asleep
  • a feeling of relaxation before going to bed
  • fewer awakenings during the night (particularly those experiencing sleep issues due to pain)
  • “turning off” racing thoughts

This is why sleep is often mentioned as a secondary benefit of medical cannabis in discussions around treatment of pain, spasticity and/or nausea.

2) A major caveat to the above: sleep quality ≠ sedation

Being sleepy is not the same as having good quality restorative sleep. Many of the studies assessing the impact of cannabis on sleep have indicated that cannabis has an impact on sleep architecture (i.e., the distribution of sleep stages). In addition, the long-term picture is more complex than initially thought particularly with respect to the potential negative impacts associated with regular use of THC.

Some of the potential negative consequences of using cannabis regularly (especially THCs) include:

  • lower amounts of REM sleep (the stage of sleep that is believed to be related to dreaming and emotional processing);
  • increasingly fragmented sleep as the body becomes accustomed to the sedative effects of THC;
  • next-day grogginess (“brain fog”) or impaired alertness;
  • tolerance to the sedative effects of THC (i.e., needing increasingly larger doses to achieve the same level of sedation).

3) What happens when you switch from occasional to daily use?

There is considerable evidence to suggest that the difference between occasional and daily/near-daily use of cannabis produces different outcomes.

For example:

  • occasional use can lead to:
  • easier sleep onset (for a short period of time);
    possible mild impairment the next day depending upon the amount of THC taken;
  • daily/nearly daily use will increase the likelihood of developing:
  • tolerance to the sedative effects of THC;
  • physical dependence on cannabis to fall asleep;
  • sleep disturbances (e.g., rebound insomnia) upon cessation of cannabis use.

In essence, cannabis can function as a “sleep crutch”: effective for a little while, then less effective and difficult to stop using once dependence develops.

4) Cannabis withdrawal and rebound insomnia exist

A number of clinical reviews have shown that stopping heavy cannabis use can result in withdrawal symptoms which can negatively impact sleep, such as:

  • insomnia or difficulty remaining asleep;
  • REM sleep rebound characterized by vivid nightmares/dreams;
  •  irritability and restlessness at night.

These symptoms can form a vicious cycle: poor sleep upon cessation → using again to fall asleep → stronger habit over time.

5) THC and CBD: two very different sleep stories

Separate consideration should be given to the distinct sedative properties of THC and CBD:

THC (intoxicating):

  • has been demonstrated to have a sedative effect on some users and shorten the time to fall asleep in the short term;
  • has the greatest potential to alter sleep stages (and therefore could produce daytime impairment) and develop tolerance and dependence patterns in users;
  • is associated with the highest degree of tolerance and dependence patterns among cannabinoids.

CBD (non-intoxicating):

has been demonstrated to have an indirect anxiolytic effect on some users and could potentially promote relaxation;
 may produce alertness in some users (contrary to sedative effects);

product quality and dosing are significant factors in determining the efficacy and safety of CBD products.

6) Cautions for specific populations

Based on the available research, the following groups would be wise to proceed with caution:

  • teens/young adults (developing brains + increased risk of dependence);
  • users with pre-existing anxiety/panic disorders (THC may exacerbate these conditions);
  • users with a history of psychotic episodes or familial predisposition to psychosis;
  • drivers/users of machinery that require early morning shifts;
  • users of alcohol/sedatives in combination with cannabis.

Practical takeaway for UK readers

While cannabis can provide short-term relief of sleep issues caused by pain or stress, frequent THC use can also damage sleep quality, contribute to tolerance, and ultimately impair sleep when attempting to discontinue use.

Please see the remainder of our blog series on marijuana in the UK.