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Abstract Introduction Insomnia and Alcohol Use Disorder are highly comorbid and share a bidirectional relationship. However, little research has examined which factors contribute to this alarming relationship. Contributing factors may include circadian preference (specifically eveningness), depression symptom severity, and global stress levels. Here, we used cross-sectional baseline data from two randomized control trials of an online CBT-I treatment program in samples of heavy drinkers with insomnia in order to elucidate whether these factors moderate the relationship between drinking behaviors and sleep. Methods Heavy drinking men and women with insomnia (n = 238) completed measures of drinking behaviors (Alcohol Use Disorder Identification Test), insomnia severity (Insomnia Severity Index), circadian preference (Composite Morningness Scale), depression (CESD-R), and global stress (Perceived Stress Scale) during the baseline phase of an online insomnia treatment study. Baseline data from two randomized control trials were pooled together for these analyses. Hierarchical linear regressions were used to examine the interactive effects of circadian preference, depression, and stress on the relationship between insomnia and drinking behaviors. Significant interactions were probed using bootstrapped estimates of simple slopes. Results Evening preference was associated with higher ISI scores (p = .02), and a trend level association with higher AUDIT scores (p = .07). However, no significant interactive effect was found between CSM and ISI scores on the AUDIT (p = .86). In contrast, significant interactions were found between the CESDR and ISI (p = .02) and PSS and ISI (p = .02) on the AUDIT. Specifically, there was a positive relationship between the ISI and AUDIT for those with either high or moderate CESDR or PSS scores (ps ≤ .05) but not for those with low CESDR or PSS scores (ps ≥ .77). Conclusion These findings suggest that the relationship between insomnia and drinking behaviors are strong among those with high to moderate levels of depression or stress but not among those with low levels. In contrast, circadian preference does not appear to impact the relationship between insomnia and drinking behaviors. Future longitudinal and treatment studies should further investigate the role of depression and stress on this problematic relationship. Support (if any) NIAAA R21 AA029201 & T32 AA027488
Verlinden et al. (Sat,) studied this question.