Daily associations between sleep and alcohol use among veterans: Acute and cumulative effects.

Background and aims: Military veterans demonstrate high rates of heavy drinking and insomnia, but few if any studies have tested real-world, daily associations between sleep and alcohol use within this population. Moreover, although daily diary and experimental studies among civilians have found negative associations between alcohol use and sleep, these patterns change with consecutive days of drinking and may differ for those with insomnia. This study measured (a) acute and cumulative day-level associations between sleep and alcohol use among heavy-drinking US veterans and (b) the extent to which insomnia moderates these associations.

Design: Self-reported ambulatory assessments occurring daily for 14 days.

Setting: USA.

Participants: Heavy-drinking veterans (n = 118, 84% male, 79% White, M = 39y) with sleep complaints. Seventy-one met criteria for insomnia disorder.

Measurements: Participants completed a semi-structured clinical interview and baseline self-report measures, followed by 14 consecutive days of morning sleep diaries. Data were analyzed using multilevel models.

Findings: Insomnia moderated day-level associations between alcohol use and sleep. Heavier drinking was associated with worse same-night sleep quality among those without insomnia [b = -0.06; 95% confidence interval (CI) = -0.09, -0.03], but this pattern was not statistically significant among those with insomnia (b = 0.02; 95% CI = -0.01, 0.04). Similarly, more consecutive nights of poor sleep efficiency were linked to lower drinking quantity among those without insomnia [incidence rate ratio (IRR) = 0.91; 95% CI = 0.83, 1.00), while better sleep efficiency was linked to heavier next-day drinking among those with insomnia (IRR = 1.01; 95% CI = 1.00, 1.01). More consecutive nights of drinking were linked to shorter sleep duration, regardless of insomnia status (b = -0.09; 95% CI = -0.18, -0.002).

Conclusions: US military veterans with insomnia do not appear to experience the same negative day-level associations between alcohol use and sleep that those without insomnia report. However, over time, drinking is linked to worse sleep in both groups.