Cannabis & Dreaming

It is commonly reported by many oneironauts that smoking or ingesting cannabis before sleep dramatically reduces the ability to recall any dreams from that night. When regular cannabis smokers take a break from using cannabis, they often find their dreams are more bizarre and vivid than usual, as a result of the 'REM rebound effect'. 

Cannabis (or marijuana) is known to affect various stages of the sleep cycle, not just REM sleep. Some of the sleep activities affected by cannabis use are not involved in the dreaming process. The chemicals found in cannabis - cannabinoids - closely mimic the activity of chemicals found naturally in the brain. These chemicals and their biological pathways constitute the body's endocannabinoid system which is responsible for regulating sleep; this will be unsurprising to many who are familiar with the effect of smoking or eating cannabis. THC (tetrahydrocannabinol) has been found to ease insomnia and quicken the sleep process for non-insomniacs alike. This was confirmed in a study by Cousens & DiMascio (1973) who studied the effects of THC as a hypnotic, testing a sample of 9 insomniacs. The same result - quickening of the sleep process - was found in non-insomniac subjects in a study by Gorelick et al (2013). A study into THC and cannabidinol use by Carlini & Cunha (1981) found that cannabis had both hypnotic and anti-epileptic effects on subjects. Taking either substance before sleep was found to significantly increase the overall length of sleep, although with some higher doses, the subjects reported 'hangover' type feelings the morning after, which were not reported in subjects administered with the lower dosages. Cannabis has also been found to increase the amount of time sleepers spend in deep (delta/slow-wave) sleep stages, the part of the sleep cycle in which restorative and reparative processes occur - see Feinberg et al (1975). A study into the effect of illicit recreational drugs on sleep by Schierenbeck et al (2008) confirmed this with empirical evidence. While deep sleep is increased with cannabis use, the one downside for dreamers is the fact that REM sleep is noticeably reduced, leading to a consequential loss of dreaming.

Strangely, cannabis use has also been found to have benefits for some sufferers of sleep apnea (25% of males and 9% of females with the condition). Sleep apnea has been linked to a number of other health problems, including diabetes and heart disease. Researchers are now trialling cannabis (in pill form, named 'dronabinol') as an alternative treatment to the disorder, which causes pauses in breathing during sleep. Initial studies by Prasad et al (2013) had positive results which they are hopeful will be replicated in a larger-scale research study.This is optimistic - currently many sufferers of sleep apnea leave their condition untreated and those who do seek medical help are encumbered by a sleep mask, which is uncomfortable and often disregarded as a long-term solution.

So, the main effect that cannabis use has on dreaming, is to reduce the amount of time the sleeper spends in REM (rapid eye movement) stages of sleep, the period in which most dreaming occurs. During the night, the sleeper will experience 4 stages of sleep, spending the longest periods in deep sleep and REM sleep.

1. Stage 1 - A very light stage of sleep which occurs at the beginning of sleep and lasts 5 - 10 minutes. The sleeper can be awakened very easily and if aroused, the sleeper will believe they were fully awake.
2. Stage 2 - A period of light sleep which lasts approximately 20 minutes as the body prepares itself for deep sleep. The temperature drops and the heart-rate slows.
3. Stage 3 (slow wave/deep sleep) - A deep period of sleep which lasts approximately 30 minutes. Delta brain waves are slow as blood flow is directed away from the brain and towards the muscles, restoring physical energy. If the sleeper is aroused during this stage of the sleep cycle, they usually feel disorientated and groggy.
4. Stage 4 (REM sleep) - The longest stage of sleep, during which most of our dreams occur. This stage of the sleep cycle is characterised by increased breathing and heart-rate and rapid eye movements. The paradoxical states of heightened brain activity (for dreaming) and muscle paralysis/immobilisation are also key features.

The REM and slow wave stages of the sleep cycle are closely interrelated; the longer you spend in deep sleep, the less REM sleep you experience If you become sleep deprived, the brain will automatically compensate for the previous lack of deep sleep, which again, lessens the amount of time spent in REM sleep. This is because the damaging effects of sleep deprivation are thought to be caused by a deficit in the restorative deep sleep, during which the body and brain heals and repairs itself from daily wear and tear. Using cannabis before bed has also been found to reduce the density of rapid eye movements in sleepers, a confirmed in a study by Lucidi et al (1996), although lower density of rapid eye movement has been linked to a more restful, relaxing sleep, so it is not all bad news! Most of the studies on cannabis and sleep have focused on the effects of THC, but in contrast, some research suggests that the other compounds in cannabis - namely, CBD - may interfere with the effects of THC and even promote wakefulness - see Nicholson et al (2003).

Regular cannabis smokers find that they experience an atypically high amount of REM sleep when they quit or take a break from cannabis use. The REM rebound effect leads to longer, denser amounts of REM sleep, during which many oneironauts or test subjects report extremely vivid, easily recalled dreams. The sleep distrurbances which occur during withdrawal from cannabis onset around 24 - 72 hours after cessation of cannabis use and may persist for up to 6 - 8 weeks afterwards, which is one positive aspect for oneironauts and dream explorers! However, the REM rebound effect is not unique to cannabis use; other substances which interfere with the sleep cycles - such as alcohol and medications - may also cause REM rebound, much the same way that sleep-deprived individuals undergo a deep-sleep rebound effect when they finally get to sleep. This is an amazing example of how the brain seeks to finely tune and balance the sleep cycles to ensure our wellbeing and health - and also points to the biological necessity of REM/dream sleep, which has been perceived by some, as being of secondary importance to deep sleep, because the latter tends to be 'prioritised' over the former, when an individual is deprived of sleep. Studies into the effect of substances on REM sleep and the REM rebound effect may shed new light on how the body and brain copes when deep sleep in nurtured and the sleeper is deprived of REM sleep only. This may help scientists discover the true nature of REM sleep and why it is so important to our emotional, mental and physical health. However, some research has indicated that spending more time in REM sleep may be linked to depression and other forms of mental imbalance. Because the brain is very active during REM sleep, it is likely that this stage in the sleep cycle is not responsible for rest or repair of the brain and that deprivation of REM sleep impacts little on memory or learning. 

Further, there have been indications that medical cannabis could be used to help treat those who suffer from nightmares or post-traumatic stress disorder. Clinical trials have confirmed that because cannabis interrupts REM sleep, synthetic cannabinoids may be successful in reducing nightmares, with 73% of subjects experiencing significant reduction or cessation.