Dreading Tomorrow, Dreading Today: Additive Effects of Evening Stress Anticipation and Sleep Quality on Morning Stress Anticipation

When people are expecting a stressful upcoming day, they tend to sleep poorly; sleeping poorly in turn has been linked to expecting a more stressful upcoming day. These mutual associations have led researchers to assume a mediating effect of evening stress anticipation on morning stress anticipation via nightly sleep. One important gap in these considerations is that people are likely able to predict how stressful the next day will be, as indicated by substantial associations of evening stress anticipation and next-day well-being irrespective of sleep. In the present study, we thus aim to disentangle time-ordered associations among evening stress anticipation, sleep, and morning stress anticipation in a 2-week ambulatory assessment study. A sample of 126 young adults (Mage = 21.5 years, SD = 2.7, 84.1% women) rated their stress anticipation for the upcoming day every evening and the next morning. Additionally, they reported their sleep quality and duration each morning and wore a smartwatch to track their sleep. Results from two-level structural equation models showed that evening stress anticipation predicted lower self-reported sleep quality, which predicted morning stress anticipation. The findings did not support a mediating process but rather an additive effect of sleep quality on morning stress anticipation beyond stability of evening stress anticipation. There were no significant association with smartwatch measured sleep. In conclusion, stress anticipation was rather stable overnight, but an additional effect of sleep quality suggests morning stress anticipation appraisals may be affected by reduced available resources following poor sleep.