CBD can have opposite effects on your sleep, depending on how much is taken.

Cannabidiol (CBD)—derived from medical marijuana—has numerous medically relevant properties.

CBD is credited with anti-anxiety, anti-psychotic, antidepressant, anticonvulsant, and neuroprotective activities in the body, among others. The latter means it may protect your brain and nervous system from damage that could result in diseases such as Alzheimer’s.

But what about its effects, if any, on sleep? Does CBD promote good sleep—or interfere with it? The answer, unfortunately, is quite complicated.

What is CBD?

CBD is one of two primary bioactive components in Cannabis sativa (also known as marijuana). The other is THC.

Unlike THC, which is responsible for many of the psychoactive effects of marijuana, CBD does not appear to elicit feelings of euphoria or other effects typically associated with marijuana use. Rather, CBD has been shown to provide numerous benefits.

As noted above, CBD may help reduce anxiety, combat depression, suppress or prevent inappropriate electrical activity in the brain (epilepsy), quell inflammation, and perhaps help prevent the development of certain neuropsychiatric disorders.

In short, CBD may well account for many of the numerous documented and purported beneficial properties of cannabis.

As noted in a 2012 issue of Philosophical Transactions of the Royal Society B: Biological Sciences, “CBD is a safe compound with a wide range of therapeutic applications, including the treatment of psychiatric disorders.”

CBD and Sleep

But what about CBD’s effects on sleep and wakefulness? The answer is more difficult to pin down than you might imagine.

In animal studies, varying doses of CBD have been administered, often directly into specific areas of the brain. A fairly well-documented pattern emerges: CBD’s effects on the sleep-wake cycle are biphasic.

In other words, CBD appears to have opposite effects on sleep, depending on the dosage administered.

Animal Studies

Doses in the low range typically have an activating effect on lab rats. Conversely, higher doses of CBD (10-40 mg/Kg) tend to promote additional sleep.

The “total percentage of sleep” increased significantly among rats given the higher doses, according to a 2013 study published in the Journal of Psychopharmacology.

However, in a 2006 study, rats that were given microdoses of CBD spent less time asleep and more time awake during the test period.

Human Studies

Small studies involving healthy human volunteers appear to mirror these findings. Larger doses of CBD (600 mg/day) were associated with more time spent sleeping in one study.

Even relatively lower doses (160 mg/day) were linked to more time spent sleeping among volunteers who complained of an inability to fall asleep or to remain asleep.

In the study, those who received CBD reported sleeping longer, with fewer periods of wakefulness or restlessness. CBD use also appeared to impact dream recall, but subjects reported no feelings of “hangover” the following day.

The decline in dream recall appears to reflect a possible reduction in time spent in REM sleep; the stage of sleep associated with dreaming.

It is perhaps for this reason that CBD has been associated with relief from nightmares among people suffering from PTSD.

Conversely, when CBD is given in low doses (15 mg/day or less) or in combination with THC, subjects typically report feeling more stimulated rather than drowsy.

In essence, these studies suggest that humans react to CBD much like other mammals do: At low doses CBD is stimulating; at high doses it is sedating.

Indica vs. Sativa Explained



This paradoxical effect of CBD helps explain some of the misinformation regarding the perceived differences between the two types of cannabis: indica and sativa.

Some people have suggested that indica strains are more likely to have a sedating effect.

But the relative concentrations of CBD and THC in any given strain likely have more to do with selective breeding for specific characteristics, regardless of strain, rather than an inherent difference in production of these compounds.

In other words, some strains may simply be bred and/or cultivated to favor higher concentrations of a particular compound.

“The sedation of the so-called indica strains is falsely attributed to CBD content,” explains Ethan Russo, M.D. in a recent interview, “when, in fact, CBD is stimulating in low and moderate doses!”

Dr. Russo is a board-certified neurologist and long-time advocate for medical cannabis research.

If anything, according to a 2004 study conducted using human volunteers, THC causes feelings of drowsiness, not CBD. In that study, 15 mg of THC had sedative effects when administered one hour before bedtime.

In contrast, 15 mg of CBD appeared to have “alerting properties”. And when given together, CBD appeared to counteract some of the “residual sedative activities” of THC.

Furthermore, a detailed chemical analysis of various samples of cannabis from both species, conducted at Indiana University’s Department of Biology, revealed that indica strains are more likely to possess a higher THC/CBD ratio compared to sativa strains.

Indeed, according to the results of a 2014 survey of medical marijuana users, a majority of users preferred indica strains for help falling asleep.

This suggests that insomnia sufferers are better off choosing strains with higher, potentially more sedating, levels of THC. The survey was relatively limited in scope, however, so additional research is required to confirm these findings.

Related Studies

Since ancient times, cannabis has been used to address various maladies, including insomnia. More recently, however, the prohibition against cannabis has hampered serious scientific inquiry.

But some data still exists. Brazilian researchers, for example, have been conducting small human studies on the effects of cannabis—as well as its active constituents, THC and CBD—for decades.

Among other findings, these investigators confirmed there is no “subjective or physical symptom” that would suggest any toxic effects from either acute or chronic doses of CBD.

Likewise, in 2015, the influential Journal of the American Medical Association (JAMA) published a meta-analysis—an overview of multiple relevant studies—to arrive at several intriguing conclusions about the potential merits of cannabinoids for medicinal use.

After evaluating evidence from 79 trials, involving more than 6,000 subjects, the authors concluded: “There was …evidence suggesting that cannabinoids were associated with improvements in nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders, and Tourette syndrome.”

While this sounds equivocal, at best, it reflects the need for additional research, and suggests that medical marijuana may indeed be useful for the treatment of insomnia, in some cases.

Summary

At low doses, CBD appears to act as a stimulant. Test subjects given small doses of CBD spent more time awake and were less inclined to fall asleep in studies.

THC, on the other hand, seems to cause drowsiness and help with sleep. The combination of these two cannabinoids, usually found in most cannabis strains, may prevent either effect from dominating.

As to the sleep-inducing effect of CBD? It likely only occurs at exceptionally high doses (160-600 mg/day).