Study objectives: Military veterans often suffer from chronic pain and sleep issues at a greater frequency than the general population, leading some to self-medicate with alcohol. While research shows a connection between sleep and pain, few studies have examined bidirectional links between sleep and pain at the daily level-or the extent to which alcohol use may moderate these associations.

Methods: Heavy-drinking veterans seeking treatment for insomnia (N = 109, 82.5% male, mean age 38.9 years) completed 14 days of morning diaries documenting sleep patterns, pain intensity, and alcohol consumption. Multilevel modeling examined within- and between-person associations between sleep (quality, duration, and efficiency) and next-day pain as well as pain and same-night sleep.

Results: Individuals with longer sleep duration, better sleep quality, and higher sleep efficiency (SE) reported lower pain levels compared to those with shorter sleep, poorer sleep quality, and lower SE (p values <.001 to .01). In addition, on days when individuals experienced better sleep quality compared to their own average, they reported lower pain levels the following day (p = .01). In contrast to hypotheses, daily pain levels did not predict sleep outcomes at the daily within-person level, although significant between-person correlations were noted. Daily alcohol intake did not affect these relationships.

Conclusions: Sleep quality is associated with the daily experience of pain among heavy-drinking veterans with insomnia. Daily variations in sleep quality significantly impact pain, irrespective of alcohol consumption, highlighting a predominantly unidirectional influence from sleep to pain. These findings underscore the importance of optimizing sleep to mitigate pain in this population.