melatonin and cannabis

Recent legalization of cannabis use: effects on sleep, health, and workplace safety

Nicole P Bowles

Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA

Maya X Herzig

Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA

Steven A Shea

Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA

The recent legalization of cannabis for medical and recreational use in many states in the United States and internationally4,5 has resulted in a decrease in stigma and of perceived risk of cannabis use, more frequent use of cannabis, use of higher potency cannabis products, and increased dependence on cannabis use.6–8 Cannabis sativa and its derivatives are often used for improved sleep and relaxation; characteristics originally attributed to Indian hemp in the nineteenth century.1–3 Cannabis alters the sleep–wake cycle, increases the production of melatonin, and can inhibit the arousal system by activating cannabinoid type 1 (CB1) receptors in the basal forebrain and other wake-promoting centers.9–12 Investigations have shown that the major psychoactive compound in cannabis, Δ 9 -tetrahydrocannabinol (THC), can decrease sleep onset latency in naïve users or at low doses in experienced users (eg, 70 mg/day); however, higher doses in experienced users increased sleep latency and wake after sleep onset.9,13,14 Indeed, frequent cannabis users (≥5 uses/week for 3 months and lifetime use ≥2 years) are reported to have shorter total sleep duration, less slow wave sleep, worse sleep efficiency, and longer sleep onset compared to controls.15 The contrasting benefits of THC exposure may represent the biphasic influence of THC on CB1 receptors whereby acute use causes more activation of CB1 receptors and tendency toward sleep, but long-term use results in desensitization of the CB1 receptor and decreased downstream signaling.

Any study of the effects of cannabis on sleep should take into consideration the route of ingestion, strain of cannabis, dose, prior cannabis exposure, and the method to quantify sleep. In this regard, it is noteworthy that over the last two decades, the average THC concentration has tripled and the products available for sale contain much higher concentrations than those that were generally available for laboratory studies.16–19 In addition to THC, hundreds of other compounds exist in cannabis products such as the non-psychoactive cannabidiol, cannabinol, and terpenes, which can also impact sleep and wakefulness.9,12,20 Individuals who obtain cannabis at medical dispensaries or for recreational use are also more likely to use alternative ingestion methods including edibles, concentrates (eg, dabbing), or extracts applied topically as oils or balms.21–23 Studies on the impact of these ingestion methods are limited, and the health consequences specific to vaping and dabbing remain largely unknown. For example, absorption rate and bioavailability are dependent upon the route of ingestion.24 Although the initial psychoactive effects of digested cannabis take longer to be felt, these effects are longer lasting compared to inhaled cannabis, which can often lead to overconsumption of cannabis compounds.25 The effects of cannabis are also dependent on weight, metabolism, gender, and prior digested meals.24,25 Given these complexities, prior laboratory studies are unlikely to reflect the users’ naturalistic experiences of sleep and of cannabis use in the present day.

The greatest body of medical cannabis research centers around pain management, while sleep appears sparingly as an ancillary result of these studies. In a randomized trial of 21 patients with chronic pain, significant improvements in sleep onset and sleep maintenance were found with a thrice-daily controlled administration of smoked cannabis (9.4% THC) compared to a placebo control.18 This suggests that the use of cannabis in place of opioids for pain management could be beneficial, but we are not aware of a head-to-head comparison of opioids versus cannabis with pain and sleep as outcomes. However, there may be some indirect evidence such as the 2014 mean annual opioid overdose mortality rates, which were 24.9% lower in states with legalized medical cannabis than in those without.26 On an individual basis, patients using both cannabis and prescription pain medication have rated the efficacy of cannabis better for pain management and indicated improved sleep, quality of life, and a preference to reduce reliance on pain medication.27,28

The legalization of cannabis use inevitably brings concerns regarding the possibility that cannabis might impair workplace performance and safety. Results from the 2015 National Survey on Drug Use and Health indicate that more than 13% of adults used cannabis in the past year and over 8% within the last month.29 This is consistent with a 2006 report of past-year cannabis use in 11% and past-month use in 5% of the surveyed workforce with more than 3% of that population also reporting cannabis use at work during the past 12 months.30 Concerns about workers’ cannabis use range from acute physical and decision-making impairments to long-term cognitive deficits.31,32 Occupational health guidelines are emerging to keep pace with increased cannabis legalization.32,33 However, the evidence supporting these recommendations is as sparse and as inconsistent as the sleep data. In a recent study of simulated shift work, smoked cannabis in frequent users (3.6% THC) was found to lessen the impairments in attention and performance during a night shift schedule.34 While there are few studies examining the risk of accidents in the workplace after exposure to cannabis, motor vehicle operation can serve as a model for performance of tasks involving safety. Individual user’s opinions on cannabis-intoxicated driving vary wildly, as does the quantitative data.35 For example, one group found significant increases in vehicle crash fatalities in California after decriminalization of cannabis use in 2012; however, a more recent study found no significant differences in the three years after recreational legalization in Colorado and Washington.36,37 In a meta-analysis of observational studies from 1982 to 2015, THC intoxication detected via blood, saliva, or urine tests was associated with a “low to medium magnitude” increase in motor vehicle crash risk.38 On the other hand, a case–control study of workplace accidents found no significant difference in risk between workers who tested positive for cannabis on a urine drug test versus a random sample of workers.39 A problem with any such study is that THC is a fat-soluble compound and remains in the body and is detectable in urine for many days after the other effects have worn off. This limitation of not being able to detect and distinguish recent cannabis use via biological samples has likely contributed to the variability of empirical data and inconclusive or unsatisfactory recommendations. The growing workplace concerns demand targeted investigation to educate both employers and employees of dose–response effects of cannabis and daytime sleepiness, and to better inform workplace safety and health guidelines.

The future of cannabis research provides many avenues for discovery. While pain reduction and sleep promotion seem promising applications for cannabis use, there are still many unknowns. Broadly, there is a need for increased research to increase potential benefits while reducing harm. Specifically, there is a need for investigations of naturalistic cannabis use, its effects on sleep, and implications for safety. These studies could inform educational campaigns to promote healthy consumption of cannabis and evidence-based guidelines for public health and workplace safety.



The authors report no conflicts of interest in this work.

Recent legalization of cannabis use: effects on sleep, health, and workplace safety Nicole P Bowles Oregon Institute of Occupational Health Sciences, Oregon Health & Science University,

Melatonin and Weed: What Happens When You Mix Them

The exact relationship between cannabis and melatonin is yet to be fully understood by science, which prevents us from forming any definitive conclusions.

There are several aspects to cover, and the most important ones are:

  • Does cannabis influence melatonin levels?
  • Does cannabis interact with melatonin supplementation?

Before we get into their convoluted relation, we should first spend some time getting acquainted with melatonin.

Most people know that it’s an over-the-counter supplement that helps us fall asleep, but melatonin is actually a truly fascinating molecule.

An introduction to melatonin

Melatonin is a naturally occurring body-produced hormone, and its main function is to regulate the circadian rhythm (also known as the sleep-wake cycle).

The circadian rhythm is a natural biological internal process that repeats itself approximately every 24 hours.

This rhythm is observed in plants, fungi, animals and humans, and is driven by the circadian clock.

The circadian clock (also known as the circadian oscillator) is an evolutionary internally-synchronized mechanism which allows an organism to predict environmental changes, and accordingly fine-tune its biological responses.

This graphic helps clarify the numerous internal mechanisms of the circadian clock.

The main role of melatonin is to prepare the body for sleep, and this effect is achieved through several interlocking mechanisms.

Firstly, the retina (which is the light-sensitive layer of the eye) sends electrical impulses to the SCN (suprachiasmatic nucleus), a miniscule region within the brain.

The SCN receives the “brightness” data from the retina, and depending how “bright or dark” the data, sends new electrical impulses to the pineal gland, which is responsible for the secretion of melatonin.

The cooperation of these three systems (retina, SCN and the pineal gland) is how the human body produces melatonin, and it is completely intertwined with the circadian rhythm.

Melatonin production begins when night starts (courtesy of darkness), and stops when the day begins (courtesy of light), preparing the body to be awake.

Now we should check out the available research on melatonin and cannabis.

Melatonin and cannabis

While the effects of cannabis on sleep are well known (and undeniably complicated as they depend on numerous factors including type of weed, quantity, frequency of use, time of consumption and so forth), the relationship between cannabis and melatonin is severely unresearched.

Rare mentions of melatonin in regards to cannabis come from a 2017 study (1) from the Oregon Institute of Occupational Health Sciences.

In it, the research team states:

Cannabis alters the sleep–wake cycle, increases the production of melatonin, and can inhibit the arousal system by activating cannabinoid type 1 (CB1) receptors in the basal forebrain and other wake-promoting centers.”

The aforementioned study was also quoting an older research from 1986 (2), which was observing melatonin levels in nine male volunteers (ages 29 to 33), after consuming a joint containing THC, and a regular cigarette without any THC.

This research found that after using cannabis, eight out of nine participants had a significant increase of melatonin in the blood.

Two additional aspects that the scientists also cited are frequency of use, and quantity of consumed cannabis.

According to their analysis, THC lessens the time required to fall asleep in occasional users, but also in frequent users (only in low doses).

High doses of THC in frequent users can cause increased sleep latency (more time required to fall asleep), shorter duration of sleep, and less slow-wave sleep (also known as the “deep sleep” phase).

What happens when you mix melatonin and weed?

Before we get into this paragraph, it’s important to note that no research was performed on the combined effects of cannabis and melatonin, and therefore we don’t condone or advise the use of these substances in unison.

The advised dose for melatonin is between 1 and 3 milligrams, and it’s also recommended not to consume melatonin supplements for a period longer than two months.

It’s also relevant to mention that since both melatonin and cannabis are safe substances, combining them infrequently and responsibly should not bring about any serious adverse effects.

The main sensations from anecdotal reports are closed-eye hallucinations (also known as closed-eye visualizations), and the ability to experience intense dreams while being high.

These reported closed-eye hallucinations resemble dream-like states where the users vividly visualize the thoughts that are going through their head, while they’re still awake.

The second effect is also undoubtedly fascinating, mostly because the majority of cannabis users don’t dream after using weed.

This happens because cannabis prolongs the deep-sleep phase of sleep, which reduces the time spent in the REM (rapid-eye-movement) phase, which is the stage where intense dreaming occurs.

It seems that the presence of melatonin changes something within the brain, which allows users to both experience and remember their dreams while under the influence of weed.

This effect could be considered useful, as it’s pretty frustrating to miss out on dreaming all the time, which affects heavy cannabis users the most.

Contrarily, the lack of dreaming can be extremely beneficial for other people, for instance PTSD patients, who suffer from recurring haunting nightmares.


Natural melatonin production is crucial, and much more important than using supplementation.

Ways to achieve this is to keep lighting low before you go to sleep (no phone/computer/TV), sleeping in pitch-black darkness, and making sure not to turn on the lights if you’re taking a trip to the bathroom in the middle of the night.

Morning or afternoon daylight/sunlight exposure are also beneficial for your body’s ability to produce melatonin in an adequate time-frame.

Besides regulating the circadian rhythm (sleep-wake cycle), melatonin is also a potent antioxidant and free-radical scavenger (3).

This implies that sufficient melatonin levels diminishes the risk of cancer (4), and de-accelerates the aging process (among numerous other benefits).

Lab-made synthetic melatonin supplements are usually made in pill form, and liquid sublingual products act the fastest, as they are absorbed directly into the bloodstream (unlike melatonin pills which have to pass through the digestive tract).

Melatonin supplements should not be used if you’re pregnant or you’re breastfeeding, if you suffer from an autoimmune disorder, depression or a seizure disorder.

People suffering from high-blood pressure and diabetes should check with their healthcare practitioner before using melatonin supplements.

These supplements can also potentially increase blood pressure levels and raise blood-sugar in patients taking certain hypertension drugs.

To conclude, if you’re determined to experiment with weed and melatonin make sure to start low and go slow, and avoid continuous use at all costs, because we just don’t know if this combination is damaging to one’s health in the long run.

Find out how weed influences melatonin production, and what to expect when combining cannabis and melatonin together.