The moderating role of conscientiousness in the temporal association between stress and sleep

The personality traits neuroticism and conscientiousness have been associated with sleep problems and the experience of stress. However, the impact of personality on objective sleep and on the temporal relationship between stress and sleep has remained elusive. This study therefore examined whether daytime stress predicts sleep the following night and the moderating role of neuroticism and conscientiousness in this relationship. To introduce stress variability in natural daily stressors, we measured college students (N=99; mean age 21 years; 86% female) during exams (e.g. high academic stress) and at the start of new course period (e.g. low academic stress). Both objective (actigraphy) and subjective sleep, and daily self-reported stress, were measured for 14 days and personality traits once at the end of the study. Results showed that reported daily stress was significantly higher in the exam period compared to baseline suggesting that our natural manipulation did indeed resulted in variation in stress levels. Intra-individual daily variations in stress were not associated with the following night's sleep timing, duration or continuity, implying that more stress during the day did not affect sleep the following night. Higher levels of neuroticism were associated with poorer daily subjective sleep quality and higher stress levels over the complete period. Neuroticism did not moderate the temporal association between stress and sleep. Conscientiousness moderated the association between intra-individual stress and sleep fragmentation and intra-individual stress and wake-up time. This implied that highly conscientious participants experienced reduced sleep fragmentation and earlier awakenings after more stressful days. These results suggest an interconnected relationship among stress, sleep, and personality. Focusing on one aspect, like handling stress or enhancing sleep quality, might yield positive effects on the rest.