Quality of sleep including timing, duration, continuity and architecture have tremendous effect on vigilance, well-being, and health. Disrupted sleep either as a primary issue or secondary to other conditions such as chronic pain, depression, anxiety, or post-traumatic stress disorder, is often devastating. Most, if not all of us have experienced a sleepless night and know it's consequences on the following day. So we can all appreciate the misery caused by prolonged alter sleep.
The role of Cannabinoid in the sleep wake cycle has been studied for many years. The hypnogenic effect of cannabis is believe to be mediated by its action on CB1 receptors in the brain. Laboratory studies show that administration of THC which primarily acts on CB1 receptors, has a short term sleep promoting effect.
Long terms effects are not clearly known. In contrast, the known cycle active cannabinoids cannabidiol or CBD which does not interact with the CB1 one receptors, has wake promoting properties. This suggest that cannabinoids have a complex effect on the sleep-wake cycle and different preparations have varying effect ranging from sleep promotion to alertness.
To examine the clinical effect on cannabis on sleep, let's begin from the perspective of cannabis withdrawal. Cannabis dependence develops in a subset of users, typically, those who uses daily. This incidentally, is relevant to use for medical purposes. Cannabis dependence is associated with drug withdrawal syndrome that has been characterized in a number of sleep laboratory studies and clinical surveys.
One of the hallmark symptoms of cannabis withdrawal is sleep difficulty which has been reported by two-thirds of adults and approximately one-third of adolescents attempting to quit cannabis use. This includes difficulty falling asleep and staying asleep, recurrent nightmares, strange dreams, and nightly sweats. Sleep difficulty has been consistently rated as one of the most severe symptoms of cannabis withdrawal and it is regarded as a risk factor for cannabis lapse.
From another perspective, studies on the effects of cannabis and synthetic or plant derived cannabinoid report improvement in sleep in patients with chronic pain conditions such as fibromyalgia, neuropathic pain, multiple sclerosis, and rheumatoid arthritis, as well as post-traumatic stress disorder.
The reported improvement is based on patient report and self-completed sleep questionnaires, but not on objective sleep laboratory studies. The evidence related to smoked medical cannabis is far weaker, mainly due to the the short duration of studies undertaken. Where administration range from a single cigarette to smoking over the course of several day. Nonetheless, improvement in sleep was reported in a small randomized control trying, of 23 patients with painful traumatic nerve injuries. Even after inhaling medical cannabis for five days only, we already could notice improvement in sleep.
Further data comes from surveys on smoked cannabis, such as the Jerusalem survey. A little over 200 patients who were followed prospectively for up to six months, reported significant improvement in their sleep, measured by a tool called, Sleep Problem Index or SPI. Having said all that, we should remember that the sedative effect of cannabis is not always an advantage especially in the context of it's day time medical use.
The acute effects of cannabis use on sleep appear to be a disruption to the sleep cycle reflecting a reduction in time spent in slow wave sleep and an increase in time spent in random eye movement sleep. Withdrawal from cannabis shows an opposite trend. A secondary impact on sleep latency may be present where both use and withdrawal appear to increase the time taken to fall asleep. Other measures such as sleep time, body movements, night time awakenings and sleep quality are not consistently influenced.
Sleep problems during cannabis withdrawal were reported by approximately half of the samples reviewed and did not appear to be a consistent cause for relapse.
Paradoxically cannabis use tended to improve sleep among populations using cannabis medicinally although this may reflect an improvement in condition related symptoms which reduce sleep.
Prof. Elon Eisenberg