Medical cannabis and insomnia in older adults with chronic pain: a cross-sectional study
Sharon R. Sznitman, Simon Vulfsons, David Meiri, Galit Weinstein
BMJ Supportive & Palliative Care, 2020, 0, 1–6.
doi : 10.1136/bmjspcare-2019-001938
Objectives : Medical cannabis (MC) is increasingly being used for treatment of chronic pain symptoms. Among patients there is also a growing preference for the use of MC to manage sleep problems. The aim of the current study was to examine the associations between use of whole plant cannabis and sleep problems among chronic pain patients.
Methods : A total of 128 individuals with chronic pain over the age of 50 years were recruited from the Rambam Institute for Pain Medicine in Haifa, Israel. Of them, 66 were MC users and 62 were non-users. Regression models tested the differences in sleep problems between the two groups. Furthermore, Pearson correlations between MC use measures (dose, length and frequency of use, number of strains used, tetrahydrocannabinol/cannabidiol levels) and sleep problems were assessed among MC users.
Results : After adjustment for age, sex, pain level and use of sleep and anti-depressant medications, MC use was associated with less problems with waking up at night compared with non-MC use. No group differences were found for problems with falling asleep or waking up early without managing to fall back asleep. Frequent MC use was associated with more problems waking up at night and falling asleep.
Conclusions : MC use may have an overall positive effect on maintaining sleep throughout the night in chronic pain patients. At the same time, tolerance towards potential sleep-inducing properties of MC may occur with frequent use. More research based on randomised control trials and other longitudinal designs is warranted.
Chronic pain is a debilitating condition that affects an estimated 19%–37% of adults in developed countries1 and is a leading cause of disability.2 Individuals with chronic pain often suffer from comorbid insomnia3 which includes difficulty initiating sleep, disrupted sleep and early morning awakenings.4 5 While chronic pain and insomnia have independent detrimental effects for individuals, their combined impact in terms of suffering and lost productivity are likely magnified.
Medical cannabis (MC) policies are changing rapidly in various jurisdictions allowing increasingly more patients legal access to use MC to ease medical symptoms from various conditions. One of the most common areas of medicine in which MC has been integrated is chronic pain.6 While there is relatively strong clinical evidence that MC is an efficacious pain reliever7 8 effect sizes are small.9 10 In addition to chronic pain, managing sleep problems has been widely reported as a motivation for cannabis use by MC patients.11 12 Research has demonstrated that the endocannabinoid system has a role in the regulation of sleep, including the maintenance and promotion of sleep.13–15
In recent years there has been a growth of randomised control trials (RCTs) that have examined the effects of cannabis on pain as a primary outcome, and sleep as secondary outcome. Despite many of these studies being of poor quality, most studies reported a significant and positive impact on sleep.7 16 Preclinical studies have, however, also shown that chronic administration of tetrahydrocannabinol (THC) is related to tolerance to the sleep enhancing effects of cannabis.5 13
Most extant studies have examined the effects of MC in the context of orally administrated synthetic cannabinoids with a 1:1 THC/cannabidiol (CBD) ratio.14 Yet, the vast majority of MC patients use the whole plant.17 18 The cannabis flower differs from synthetic cannabis-based medicines in that the former consists of over 500 different compounds.19 While THC and CBD are among the most well known compounds, others are likely to have important effects as well.20 It is possible that phytocannabinoids and various combinations of cannabinoids differ in their effects on sleep compared with THC and/or CBD alone. This process has been called the entourage effect21 and suggests that findings from studies that administer THC/CBD extracted medicines are unreliable as indications of the effects of MC used by most chronic pain patients.
The present study was designed in order to examine the association between sleep problems and MC in middle age and older (50+ years of age) chronic pain patients. This relatively old age limit was chosen as both sleep and chronic pain problems have increased incidence in late-life22 23 and the prevalence of the comorbid conditions is therefore expected to grow with the ageing population. The study builds on and complements findings from internally valid RCTs by employing a more ecologically valid, naturalistic approach. Specifically, the study examines the associations between use of whole plant cannabis and three main indicators of insomnia. We hypothesised that compared with chronic pain patients who do not use MC, MC chronic pain patients would report less sleep problems. In addition, among MC patients, we examine the association between sleep problems and different patterns of MC use. Due to the potential tolerance building effects of chronic MC administration noted in preclinical studies5 13 we expected that length of MC treatment, frequency of use and higher dose and THC concentrations would be associated with more sleep problems.