While cannabis use is associated with subjective sleep improvements, studies employing objective sleep measures (e.g. actigraphy) demonstrate mixed relations. Based on social cognitive theory, it is possible that positive sleep-related cannabis expectancies (i.e. beliefs that cannabis will improve sleep) may modify self-reported sleep outcomes. This daily-level study examined agreement between subjective and objective sleep measures and evaluated whether positive sleep-related cannabis expectancies augmented discrepancies between subjective and objective sleep outcomes on cannabis use days. Individuals endorsing regular cannabis use and sleep motives (N = 23) completed baseline measures on cannabis use, sleep, and expectancies, followed by up to seven days of diaries and continuous actigraphy (n = 155 days). Diary and actigraphy agreement was poor for wake after sleep onset and sleep onset latency, moderate for total sleep time, and excellent for fall asleep time and wake-time. Expectancies were associated with overestimated diary total sleep time and this association was amplified on cannabis use days. Tendencies to self-report earlier diary fall asleep time on cannabis use days and later time on nonuse days were amplified as expectancies increased. Sleep-related cannabis expectancies may bias self-reported sleep, highlighting the need to account for such beliefs in future research examining cannabis-sleep relations with subjective measures.
Livingston et al. (Fri,) studied this question.