How Does Cannabis Affect Sleep?

A man with glasses resting his head on a hand clicking on the keyboard

Many regular users will at some point have experienced feelings of sleepiness and lethargy after using cannabis. This effect varies between from person to person, and may be affected by mood, existing tiredness, or even the time of day. The variety of cannabis also has a major part to play.

It’s no secret that many cannabis users find that it helps them sleep. There’s much more to it than just “smoking weed makes me sleepy”, though. For example, it can affect different stages of sleep in different ways. There are also ways to get more out of cannabis as a sleep aid, such as different strains, how fresh the cannabis is, etc. To find out, let’s first investigate how cannabis can affect sleep patterns.

Cannabis’ effect on sleeping patterns

The way in which cannabis influences sleep in humans is extremely complex and far from being fully understood, although several papers have been written on the subject. For centuries, if not millennia, people have been using cannabis as a sleep aid, reporting that they’re able to get to sleep more quickly and ultimately feel more rested.

A woman lights a joint with a green lighter

However, it’s common knowledge among those that use cannabis in this manner that there can be a “hangover” effect. This can make it difficult to wake up and leaves the user feeling drowsy and lacking in alertness for some time after awaking.

Human sleep occurs in cycles; cycles progress through four stages before beginning again:

  • The 1st stage: A state halfway between sleep and wakefulness, where the sleeper may be easily awoken
  • The 2nd stage: A light sleep which is somewhat more difficult to rouse someone from
  • The 3rd stage: Known as deep or slow-wave sleep (formerly separated into stage 3 and stage 4. It’s now considered to be one discrete stage rather than two and the fourth stage is reserved for REM.)
  • The 4th stage: Deep sleep, during which rapid eye movement (REM) occurs

Cannabis, deep sleep and REM

Sleep studies have shown that low doses of THC can cause a reduction in the duration and intensity of rapid eye movement (REM) sleep, while also increasing the duration of stage 3 deep sleep.

A woman sleeping in a bed in a dark room

A 1975 study into the effect of THC on sleeping patterns found that administration of THC at a dosage of 210mg per day over two weeks significantly reduced eye movement during REM sleep. It also slightly shortened the length of time the participants spent in the REM stage. The study also found that duration of stage 3 deep sleep was slightly lengthened after administration of THC, but this effect was not statistically significant.

A clinical review from 2008 again showed that small amounts of cannabis can increase Stage 4 sleep, total slow wave sleep and help the user fall asleep easier. However, it also showed that cannabis can decrease total REM sleep and REM density.

However, higher doses can have quite the opposite effect. High doses of THC can lead to:

  • Decreased REM sleep
  • Decreased slow wave sleep
  • Decreased sleep onset latency: The time it takes from being fully awake to sleep
  • Hallucination effects

As a review from 2015 points out, chronic use can also have varying effects. Chronic use can lead to developing a tolerance to sleep latency effects, but not so much for the effects on REM sleep.

The effects of THC and CBD on sleep

There are many reasons why cannabis may provide varying effects on sleep. Much of this may have to do with the THC and CBD content of the cannabis used, as well as the dosage and if there’s chronic use involved.

A woman lying in a bed looking at the clock

A more recent study than those above, conducted in 2004, investigated the effect of varying dosages of THC on sleeping patterns, as well as the effect of THC in conjunction with CBD. Eight volunteers were administered either a placebo, 15mg of THC, 5mg of THC with 5mg of CBD, or 15mg of THC with 15mg of CBD via oromucosal spray.

The participants were monitored using electroencephalogram (EEG) equipment. This study concluded that the 15mg THC dose without CBD had no discernible effect on nocturnal sleep, but the next morning the subjects reported increased lethargy and sleepiness, changes in mood, and impaired memory.

The combined administration of 5mg THC and CBD caused a decrease in stage 3 sleep, and the 15mg combined dose increased the participant’s feelings of wakefulness and alertness. This indicates that THC has some sedative effect that is counteracted by CBD, as participants taking the 15mg THC/CBD dose experienced increased activity while asleep, and furthermore did not experience the sedative morning-after effects of THC.

While this particular study did not note an increase in deep sleep and a decrease in REM sleep following administration of THC alone (as with the 1975 study), it has been shown in other studies that this is indeed the case. Additionally, THC appears to facilitate initial sleepiness and speeds up the process of falling asleep, although it’s not exactly clear how this works.

How does this phenomenon occur?

The process of falling asleep, and the progression of stages in a cycle, is determined by complex interactions between the neurotransmitters in the brain. The primary inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is fundamentally involved with sleep processes, and it has been shown that activation of GABA receptors can help to induce sleep. Thus, many present-day sleeping medications target these receptors.

This is important, because it’s been established that the endocannabinoid system is fundamentally linked to the GABA signalling system, and the endocannabinoid 2-arachidonoyl glycerol (2-AG) has been shown to directly activate GABA receptors. It’s possible that cannabis exerts its initial effect on drowsiness via this mechanism.

Can cannabis help treat insomnia?

There’s not enough hard data about using cannabis for insomnia. However, research indicates that CBD may very well provide therapeutic help (but probably not THC). There are also concerns among some that long-term use may product new sleep problems due to dependency or withdraw. For now, cannabis should probably be limited to helping occasional sleep problems and not as a cure for chronic sleep problems or insomnia.

Cannabis use and dreaming

REM sleep is the stage of sleep in which dreaming occurs. It’s also known as paradoxical sleep, as it involves a high level of neuronal activity—almost comparable to waking levels—along with a drastically reduced level of physical activity. In fact, the majority of muscles are actually paralysed during REM sleep, in a phenomenon believed to be associated with the tonic immobility exhibited by many prey species in the presence of certain predators.

A bulb as a hot-air balloon with a man flying in it

In animals, this tonic immobility can cause the appearance of lifelessness, which puts off predators uninterested in carrion. In humans though, it may be that this sleep-time paralysis serves a similar role of keeping us from sleepwalking into potentially dangerous situations as a result of intense or vivid dreaming.

Cannabis users all around the world report that with regular use, the subjective experience of dreaming is reduced or entirely absent, and that cessation of cannabis use causes dreaming to resume with remarkable intensity. It appears that the reduction in REM sleep caused by THC is behind this phenomenon. Ensuring that your chosen cannabis variety contains comparable levels of CBD to THC may go some way towards negating this phenomenon.

Which strains of cannabis are better for sleep?

Finding the best strain to help promote better sleep will likely take some trial and error, as there are many factors to be considered and cannabis will always have different effects from person to person. However, here are a few tips that are generally agreed upon:

  • Disclaimer:
    This article is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your doctor or other licensed medical professional. Do not delay seeking medical advice or disregard medical advice due to something you have read on this website.


4 thoughts on “How Does Cannabis Affect Sleep?”

  1. James Morrison

    I have . . . HAD severe arthritic pain in my left knee. For the last two months, I have been dropping seven drops of CBD under my tongue just before going to bed. The pain has not
    just diminished. It is gone. I have experienced absolutely NO undesirable side effects.
    According to the provider, Sisters of the Valley, the oil has less than 1% of any psychogenic material and is therefore not under the concern of any legal authorities regarding drug abuse. I am extremely grateful for the lack of pain. I suspect there are VERY few people less likely to ingest any product related to marijuana than i am. For many years, I taught a public school unit on the dangers of drug abuse including smoking pot. This just ain’t the same, folks.

  2. I have been taking cbd oil (3mg each mid-morning) and I noticed I was not getting more energy, but rather feeling more tired. I switched my dose to taking it in the early evening. Now I’m sleeping better, but I don’t feel energetic when getting up.
    I would like to know if anyone else has had these problems? Thanks, A

  3. Joe kleckner

    I have copd .I have mucus lots will thc or cbd work or do I need a different strain … Could use help,,,,,please an Thanks

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