ABSTRACT
Insufficient sleep is common among university students and impairs health and academic functioning. While multidimensional perfectionism (perfectionistic concerns and strivings) and daily stress are potential contributors, yet their interplay and underlying cognitive mechanisms remain unclear. Cognitive pre-sleep arousal may mediate links between stress, personality traits, and sleep. In a 14-day micro-longitudinal study, 88 German university students (M = 22.47 years, SD = 3.48) wore fitness trackers and completed daily diaries assessing objective sleep duration, subjective sleep quality, subjective sleep onset latency (SOL), daily stress, and cognitive pre-sleep arousal. Trait perfectionism and covariates (emotional distress, Big Five traits, and sex) were measured via questionnaires. Multilevel modelling and structural equation modelling were used. Neither perfectionistic concerns nor strivings predicted any sleep parameters. However, daily stress was associated with shorter sleep duration (b = −0.21, p = 0.033), lower sleep quality (b = −0.09, p = 0.006), longer SOL (root transformed: b = 0.01, p = 0.046), and higher cognitive arousal (b = 0.06, p < 0.01). No interaction effects between perfectionism and stress were found. Within-person mediation showed that on days with elevated stress, increased cognitive pre-sleep arousal partially explained shorter sleep (indirect effect = −0.16), lower sleep quality (indirect effect = −0.08), and longer SOL (indirect effect = 0.01; all p < 0.001). Exploratory analyses indicated that emotional distress, unlike perfectionism, predicted longer SOL via heightened cognitive pre-sleep arousal (indirect effect = 0.09, p = 0.007). Given the suboptimal model fit in the mediation models, all indirect effects should be interpreted with caution. Daily stress robustly impairs sleep and elevates cognitive pre-sleep arousal, which partially mediates its negative effects on sleep variables. Multidimensional perfectionism was not associated with sleep, nor did it moderate the stress-sleep link. Targeting cognitive pre-sleep arousal may be a promising mechanism to improve sleep in students experiencing elevated stress.