A Hidden Effect of Marijuana Use

June 15, 2008
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Findings on sleep give clinicians an opportunity to discuss marijuana's harms

Despite slight decreases in reported marijuana use among youths and adults over the past several years, marijuana is still the most commonly used illicit drug in the United States.1,2 Because it is highly improbable, although not impossible, that marijuana use will result in salient, acute negative consequences (e.g., overdose, hallucinations, blackouts, hangovers), marijuana is often regarded as a “soft drug” with relatively minor risks in comparison to other illegal drugs. Many of the detrimental effects of marijuana use involve gradual changes in functioning that develop over substantial periods of time.

Marijuana is not unlike tobacco in the sense that it is more difficult for its users to recognize its effects, and therefore easier for them to rationalize use. Still, the paradox of marijuana use is that “soft drug” or not, the potential accumulated risks can be very severe, up to and including death. The same phenomenon exists in tobacco use; the consequences of use are not as acute as those of other drugs, yet tobacco use is still the leading cause of preventable death in the United States.3

Clients in substance use treatment are often misinformed or relatively uneducated about marijuana use's effects. This article explores just one of the many areas of functioning that marijuana can affect in users: the human sleep cycle. Marijuana's impact on the sleep cycle can produce both acute and chronic effects on a person's functioning. This offers a partial physiological explanation for some of the reported effects of marijuana use.

A brief overview of the human sleep cycle and its importance in terms of daily functioning is in order. Humans sleep in five different stages, differentiated primarily by brain wave patterns measured by electroencephalography (EEG). Just prior to falling asleep, the typical person is in a relaxed state of consciousness characterized by alpha waves (a frequency of 8 to 12 waves per second). After the person falls asleep, phase one of the sleep cycle begins, during which brain activity is still fairly high but declining. When a person reaches stage two, brain waves become slower. The third and fourth stages of sleep are known as slow-wave sleep. During SWS, heart rate, breathing rate, and brain activity slow down and the percentage of slow, large-amplitude waves increases. After stage four, a person cycles back through stages three and two. However, instead of returning to stage one, the person enters a stage of sleep known as rapid eye movement (REM) sleep.

REM sleep (also known as “paradoxical sleep”) is characterized by irregular, low-voltage fast brain waves. Despite this considerable degree of brain activity, the postural muscles of the body are more relaxed at this stage of sleep than at any other stage. Dreams are more vivid, intricate, and somewhat more frequent during this stage. Short-term memory is consolidated into long-term memory. Since muscles are most relaxed during REM sleep, the body shifts its resources to the task of repairing tissues and cells—a vital task of the immune system.4,5

Since the 1970s, several studies have examined the effect of THC (the main psychoactive ingredient in marijuana) on SWS and REM sleep stages. Researchers have demonstrated that THC ingestion decreases SWS and REM sleep, and has sometimes been found to eliminate REM sleep altogether in rats, rabbits, and cats.6,7,8,9 In later research, the same effect was observed in humans in controlled studies, with the added finding that sleep cycles did not return to normal until after about one week of abstinence.10,11 Difficulty falling and staying asleep and restlessness were noted in three studies a few days after abstinence for people who smoked marijuana and for people who orally ingested THC.12,13,14

Clinical application

Clinicians can apply knowledge of marijuana's effects on sleep in several ways. In my practice I favor the change process model proposed by Prochaska, Norcross, and DiClemente.15 The model is unique in that rather than starting with a hypothesis about how change happens and then testing it, these researchers first found clients who had successfully established and maintained major life changes, then studied similarities in the change experiences that formed the basis for the Stages of Change approach.

Clinicians can best facilitate the change process when they match clients with strategies and techniques that take into consideration where the client is in the change process. For example, education on substances' effects on the body is not necessarily the most effective focus for a client who already has dedicated herself to change and is now preparing for discharge from a residential program. Dispensing information on marijuana's effect on sleep can be particularly effective for clients in the first and second stages of change: precontemplation and contemplation.

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