UK medical cannabis patients with insomnia reported improved sleep quality over 18 months | Research

The takeaway

Registry data from 124 UK insomnia patients prescribed cannabis-based products showed significant improvements in sleep quality, anxiety, and quality of life that persisted through 18 months.

Sleep medicine clinicians, medical cannabis researchers, insomnia patients exploring treatment options

Sleep quality doubled at 1 month, remained improved at 18 months

What the researchers found

Sleep quality scores (SQS) improved from 2.66 at baseline to 5.67 at one month (P<0.001) and remained significantly improved at 18 months (3.81, P<0.001), though improvements diminished over time. GAD-7 anxiety scores also improved significantly through 18 months. EQ-5D-5L quality of life showed improvements in usual activities, pain/discomfort, and anxiety/depression dimensions. Only 8.87% of participants reported adverse events, none disabling or life-threatening.

Why it matters

Current insomnia treatments have significant limitations including dependency risk and side effects. This is among the longest follow-up periods for medical cannabis and insomnia, showing sustained but declining benefits that raise questions about tolerance.

The numbers in context

n=124; SQS improved from 2.66 to 5.67 at 1 month (P<0.001); declined to 3.81 at 18 months (still P<0.001 vs baseline); 8.87% reported adverse events; 112 total adverse events recorded, none severe

How the study worked

Case series from the UK Medical Cannabis Registry (UKMCR) analyzing 124 patients diagnosed with primary insomnia who were prescribed cannabis-based medicinal products. Patient-reported outcome measures (PROMs) assessed at baseline, 1, 3, 6, 12, and 18 months. Adverse events classified per CTCAE version 4.0.

What this study cannot tell us

No control group or randomization; case series from a voluntary registry. Patients self-selected into treatment. Declining improvement over time could reflect tolerance, regression to the mean, or changing patient populations. Product formulations and doses varied across patients.

How to read the evidence

Real-world registry data with unusually long follow-up provides useful observational evidence, but the absence of a control group, randomization, or standardized treatment limits confidence.

When this study was published

2025 publication from the UK Medical Cannabis Registry

The bigger picture

The pattern of initial strong improvement followed by gradual decline is consistent with tolerance development, a concern with many sleep medications. The 18-month follow-up is unusually long for cannabis sleep research and provides a more realistic picture of real-world outcomes.

Questions still open

Does the decline in sleep improvement from month 1 to month 18 reflect tolerance? Would randomized controlled trials against standard insomnia treatments confirm these observational findings?

Common questions

Did sleep improvements last over time?

Sleep quality improved significantly and remained better than baseline through 18 months, but the magnitude of improvement declined from month 1 onward, suggesting possible tolerance effects.

Were there safety concerns?

Only 8.87% of participants reported adverse events, and none were disabling or life-threatening. However, without a control group, it is difficult to determine which events were treatment-related versus coincidental.

Read the original research

UK Medical Cannabis Registry: A clinical outcomes analysis for insomnia.

PLOS mental health, 2(8), e0000390

View on PubMed ↗Publisher’s paper ↗

Citation

Aggarwal, Arushika; Erridge, Simon; Cowley, Isaac; Evans, Lilia; Varadpande, Madhur; Clarke, Evonne; McLachlan, Katy; Coomber, Ross; Rucker, James J; Weatherall, Mark W; Sodergren, Mikael H. (2025). UK Medical Cannabis Registry: A clinical outcomes analysis for insomnia.. PLOS mental health, 2(8), e0000390. https://doi.org/10.1371/journal.pmen.0000390