A placebo-controlled experimental study in Australia on adults suffering from insomnia showed that consumption of medicinal cannabis oil containing 10 mg/ml tetrahydrocannabinol (THC) and 15 mg/ml cannabidiol (CBD) over 2 weeks improved sleep time compared to a group receiving placebo treatment. Levels of melatonin, a hormone produced by the brain that helps regulate the internal clock and sleep, were also higher in the group consuming the oil. The study was published in the Journal of Sleep Research.
“Insomnia is experienced by a third (30%) of the adult population,” said study author Karin Ried, the director of research at the National Institute of Integrative Medicine.
Insomnia becomes more common at older age and often accompanies other diseases. It has significant negative impact on daily functioning, energy levels, concentration, mood, and physical well-being of individuals suffering from it.
One of the potentially promising treatments for insomnia involves the use of medicinal cannabis oil. Medicinal cannabis is known to be helpful in relieving pain. Studies have shown that delta-9-tetrahydrocannabinol (or THC) has a sedative effect and the same is the case with higher doses of cannabidiol (or CBD). Both THC and CBD are compounds produced by the cannabis plant. A possible problem with the use of THC is that higher doses have psychoactive effects, so higher CBD to THC ratios are recommended as potential treatments for insomnia.
“Medicinal cannabis showed promise in alleviating the insomnia. However, there was a dearth of studies looking at the effect of medicinal cannabis on sleep as a primary outcome measure. To our knowledge our study is only the second randomized controlled trial looking at the effect of medicinal cannabis on sleep as a primary outcome measure.”
The researchers conducted an experimental study aiming to assess the tolerability for medicinal cannabis oil and whether taking it for 2 weeks has effects on sleep in adults with insomnia. Participants were 29 adults between 25 and 75 years old. They were required to not be shift workers and not use antidepressants. Candidates with a number of serious diseases were also excluded from participation.
Participants were randomly divided into two groups. For two weeks, participants were instructed to take the oil issued to them with food in the evening. They started with a 0.2 ml dose and were supposed to increase it by 0.1 ml each day, up to a dose of 1.5 ml. The difference was that one of the groups received cannabis oil with 10 mg/ml of THC and 15 mg/ml of CBD formulated with medium chain triglycerides and lesser amounts of other cannabinoids and naturally occurring terpenes and peppermint flavor. The oil the other group received consisted solely of the medium chain triglycerides carrier with peppermint flavor added and packaged in the same bottle.
Participants were not told which oil they were receiving and researchers found that participants were unable to tell which type of oil they were taking during the first two-week treatment phase. Participants were asked to keep a daily diary in which they recorded the dose of oil taken and any side-effects. Side-effects were also assessed after one week since the end of the intervention and at the end of the study. Daily increases in the dose of oil were halted if participants reported side effects that were greater than benefits.
The two-week treatment period was followed by a 1-week washout period, during which participants were not taking the supplied oil. This was followed by another two-week treatment period in which group treatments switched – the group that has been receiving cannabis oil during the first two-week period was given placebo oil (the one without THC and CBD) and the group that was taking placebo was given cannabis oil. In this second phase, 80% of participants were aware of which study group they are in.
Researchers used levels of melatonin in saliva at midnight as the primary measure of treatment effectiveness. Participants were instructed to collect their saliva around midnight, before falling asleep at 4 points during the study period and send it to external laboratory per instructions. Researchers used “Sleep Profile Saliva Kit” by NutriPATH, Australia to assess melatonin and cortisol levels in saliva. Participants carried a Fitbit wrist activity/sleep tracker continuously throughout the 6-week study period.
Before and after each intervention, participants completed assessments of insomnia symptoms, sleep quality (the Pittsburgh Sleep Quality Index), sleepiness during the day (the Stanford Sleepiness Scale), level of fatigue and its interference with daily activities (the Brief Fatigue Inventory), and mood (the Bond-Lader Mood Scale).
“During cannabis oil dosing, four (14%) participants had no side-effects, and 24 (83%) reported non-serious side-effects possibly related to the active medication, such as dry mouth (52%), diarrhea (27%), nausea (24%), and vertigo (17%). Importantly, all non-serious side-effects other than dry mouth were transient and experienced only on 1 or 2 non-consecutive days,” the researches wrote.
About half of the participants in the cannabis oil group got to the maximum dose of 1.5 ml over the 2-week period, while the other half stopped increasing the dose at .4 to .6 ml due to side-effects. In the placebo group, 33% reported non-serious side effects including “dry mouth (10%), diarrhea (5%), nausea (7%), tingling of tongue and lips (7%), and headache (3%).”
Results showed that mean melatonin levels at midnight increased 30% in the cannabis oil group, but decreased 20% in the placebo group. Higher melatonin levels are associated with better sleep. Insomnia symptoms significantly improved in the cannabis oil group compared to the placebo group over the 2-week treatment period. This group was able to fall asleep sooner, sleep longer and wake up less often during the night.
“Our study found significant improvements in sleep duration, quality of sleep, and – importantly – melatonin levels,” Ried explained. “To our knowledge, our study is the first to use the physiological measure of midnight saliva melatonin levels as a measure for sleep quality. Melatonin levels at midnight are high in adults without sleep issues, and low in insomniacs. Any study on sleep should include this important measure.”
Wrist tracker also showed that the cannabis oil group slept 30 minutes longer on average after two weeks of intervention compared to the start of the study. Comparatively, the placebo group slept on average 9 minutes longer after 2-weeks of treatment compared to the start. No differences between groups were found in sleepiness during the day, fatigue, sleep quality and mood as assessed using questionnaires. There were also no differences between groups in cortisol levels.
The study sheds light on potential effectiveness of cannabis oil in treating insomnia. However, it should be taken into account that the study sample was small and the study period coincided with the enforcement of very restrictive anti-COVID lockdown measures in Melbourne, Australia where it was conducted. This might have affected the results.
The study, “Medicinal cannabis improves sleep in adults with insomnia: a randomised double-blind placebo-controlled crossover study”, was authored by Karin Ried, Tasnuva Tamanna, Sonja Matthews, and Avni Sali.
