The claim that some patients report improvements in mood stability, sleep, or physical discomfort is primarily supported by systematic reviews, randomised controlled trials in specific indications, and large-scale observational registry data. Importantly, most UK guidance emphasises that benefits are condition-specific and patient-specific, which is why individual assessment is essential.
For sleep and physical discomfort, a frequently cited source is the 2017 report by the National Academies of Sciences, Engineering, and Medicine. Their comprehensive review concluded that there is substantial evidence that cannabis or cannabinoids are effective for chronic pain in adults, and moderate evidence for improvement in sleep outcomes in individuals with conditions such as chronic pain, multiple sclerosis, and fibromyalgia. While this is not UK-specific, it is widely referenced by UK clinicians due to its methodological rigour.
In relation to chronic pain, a 2021 systematic review published in the British Medical Journal analysed randomised trials of non-inhaled medical cannabis and cannabinoids. The review found small to moderate improvements in pain relief and sleep quality compared with placebo, alongside an increased risk of non-serious adverse effects. This supports the wording “some patients report improvements” rather than a universal or guaranteed benefit.
Mood stability and mental health symptoms are more nuanced. A large 2019 meta-analysis in The Lancet Psychiatry examined cannabinoids for mental health disorders and found limited evidence for efficacy in depression and anxiety disorders, but noted short-term improvements in anxiety symptoms in some patients, particularly in controlled CBD-dominant preparations. This is why UK clinics are cautious and stress personalised assessment and close monitoring.
Real-world evidence is also increasingly important. Data from Project Twenty21, the UK’s largest medical cannabis observational registry, shows patient-reported improvements across pain severity, sleep quality, and health-related quality of life over time. However, these are observational outcomes rather than placebo-controlled trials, reinforcing the need for careful clinical interpretation.
Finally, UK regulatory guidance underlines the need for individual assessment. The National Institute for Health and Care Excellence (NICE) states that cannabis-based medicinal products should only be considered where there is clear clinical rationale, previous treatments have been inadequate, and prescribing is undertaken by a specialist with ongoing review of benefits and risks.
Link to the BMJ clinical guideline on medical cannabis for chronic pain, which discusses modest benefits for pain, sleep and physical functioning alongside the need for individualised assessment:
https://www.bmj.com/content/374/bmj.n2040
Link to the National Institute for Health and Care Excellence (NICE) guideline on cannabis-based medicinal products, with recommendations about prescribing in specific conditions (chronic pain, spasticity, epilepsy, etc):
https://www.nice.org.uk/guidance/ng144
The 2017 report by the US National Academies of Sciences, Engineering, and Medicine, which summarises evidence for therapeutic effects of cannabis and cannabinoids (including for pain and sleep outcomes):
https://www.nationalacademies.org/read/24625
Excerpt from that report outlining moderate evidence that cannabis or cannabinoids can improve short-term sleep outcomes:
https://www.ncbi.nlm.nih.gov/books/NBK425741/
A clinical review summarising trial evidence on cannabis/cannabinoids for pain, noting modest benefit:
https://pmc.ncbi.nlm.nih.gov/articles/PMC5549367/
A 2022 systematic review indicating characteristics and outcomes in patients seeking prescribed cannabis through Project Twenty21:
https://www.frontiersin.org/journals/pain-research/articles/10.3389/fpain.2022.891498/epub
An example of reporting on patient-reported outcomes relating to anxiety, sleep and quality of life measures in a registry context:
https://curaleafclinic.com/outcomes-for-generalised-anxiety-disorder-from-the-uk-medical-cannabis-registry/
And, for context on the limitations and state of evidence (noting need for individual assessment and mixed quality of studies):
https://pubmed.ncbi.nlm.nih.gov/41506388/