Marijuana (cannabis) use is common, particularly before bed time. Does it help with sleep?

marijuana and sleepA surprising number of people I see use cannabis or marijuana, some socially and some to help wind down and help with sleep. But does marijuana really help with sleep and what are the negative effects of marijuana use?

What’s in marijuana?

The drug effects of marijuana or cannabis are due to chemicals known as cannabinoids that activate cannabinoid receptors in the brain. The primary cannabinoid responsible for the psychological effects of marijuana is tetrahydrocannabinol (THC). In small doses, THC tends to act as a sedative. In moderate doses it can be more stimulating and in higher doses can cause psychotic-like symptoms.
Marijuana can be consumed in a number of different ways. It is most commonly smoked, and when smoked, in addition to THC, there are particles that get inhaled in to the lungs. This occurs either when smoked or taken through a water pipe (bong). These particles can include infections such as fungi, and can cause lung problems such as bronchitis or other problems as discussed in a case report I published in Chest in 2000. To get around this, people using medical marijuana in countries such as the US, sometimes use vaporisers to absorb THC whilst avoiding the inhalation of smoke. Marijuana can also be eaten in foods. But, when eaten, it can take some time for effects to occur, whereas with smoking THC is absorbed rapidly allowing users to more carefully titrate the dose.

Marijuana and sleep

marijuana and sleepMost of the research on marijuana and sleep was done in the 1970s. In general studies show that in the short term, marijuana or THC used in low doses has a sedative effect, and can help with getting to sleep quicker and sleeping longer. THC has also been shown in the short-term to promote rapid eye movement (REM) sleep. However, in the longer term, these effects often don’t persist, much like alcohol (see this post for more detail on alcohol and sleep). This can lead to the situation where people start using marijuana to help wind down or sleep, and find whilst it helps initially, over time find they need to take more and more and it has less of an effect. Marijuana is used for medical purposes in the United States in some states. In some of these states, marijuana is used for conditions associated with poor sleep such as pain or post-traumatic stress disorder (PTSD). There is more data on marijuana and it’s effects for these conditions, hence it’s use.

What are the negative effects of marijuana use?

Like alcohol, people who use marijuana as a long-term sleep aid, run the risk of becoming increasingly reliant on it and needing to take it in increasing doses. This is a common problem I see in the clinic, where people start using marijuana to help with sleep as young adults, but end up taking increasing amounts over time, and having some of the negative effects of marijuana impact on their health and life. Negative effects from marijuana include:
  • Lack of motivation – particularly in people with a tendency to depression, marijuana can add to lack of motivation to complete tasks.
  • Psychosis – marijuana can precipitate hallucinations or psychosis particularly in those prone to anxiety or who have schizophrenia
  • Respiratory effects – as discussed above, smoking marijuana can cause other respiratory effects such as bronchitis
Although research has shown that people smoking marijuana have an increased rate of sleep problems such as insomnia, and recent research from Melbourne shows that alcohol and cannabis users report problems with sleep quality, it’s not clear from these studies whether marijuana caused the problems or is being used by people who already had sleep problems as a sleep aid.

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