Association between cannabis use and insomnia symptoms among veterans with chronic pain

Insomnia and chronic pain commonly co-occur, with Veterans more likely to experience both compared to the general population. As opioid prescribing practices change, there is growing interest in the use of cannabis for pain management and insomnia yet little data evaluating these potential associations.

405 Veterans recruited nationally who were prescribed long-term opioid therapy for chronic pain and had a positive urine drug screen for THC in the month prior were enrolled. Participants were stratified into "none" (n = 118), "mild" (n = 140), and "moderate/severe" (n = 147) insomnia groups via the Insomnia Severity Index. THC consumption over the prior ~3-6 months was determined from nail samples, assayed for Carboxy-THC (pg/mg) via liquid gas chromatography/mass spectroscopy.

Bivariate analyses compared demographic and clinical factors based on insomnia severity classifications. Relative to patients without impaired sleep, those classified as having mild insomnia had significantly worse pain interference, anxiety, depression, and PTSD symptom severity. These relationships were further amplified in the moderate/severe sleep impairment group, which also reported significantly greater pain intensity. However, no group differences were found related to Carboxy-THC concentration, reflecting previous consumption characteristics. Multivariable linear regression examined variables associated with insomnia severity; PTSD, depression, and pain interference were associated with insomnia, with no effect of cannabis consumption.

These findings suggest that in a sample of Veterans prescribed long-term opioid therapy with past month cannabis use, THC consumption may not be associated with insomnia symptoms. Future research should examine a possible threshold effect of cannabis dose on insomnia symptoms.