A new study using intensive daily sampling over one week shows that day-to-day fluctuations in emotions directly predict how well emerging adults sleep the following night.
Researchers from the University of Lausanne and the University of Fribourg followed 166 first-year psychology students aged 18 to 24 over seven consecutive days, administering four surveys per day via smartphone. The Ecological Momentary Assessment (EMA) design captured real-time emotional states and daily stress levels, then linked them to self-reported sleep quality the next morning. Compliance was high at 92.4%, yielding over 4,200 data points for analysis.
What they found
At the within-person level, comparing a person’s emotional state on one day vs. another, higher daily levels of anger, anxiety, sadness, and perceived stress each predicted significantly lower sleep quality that night. Conversely, days when participants reported greater happiness led to better sleep.
The between-person effects, comparing individuals to one another over the full study week, were even larger. People with generally higher levels of negative affect and perceived stress across the week had substantially worse sleep quality on average. Happiness at the between-person level explained 9.5% of the variance in sleep quality, the strongest effect in the study.
Among nine emotion regulation strategies assessed (reappraisal, acceptance, problem-solving, suppression, avoidance, distraction, social support, rumination), only rumination showed a significant link to sleep quality: participants who habitually used rumination more frequently reported lower sleep quality.
Why it matters
Emerging adulthood is a critical window for both emotional development and sleep health. The findings suggest that interventions targeting daily emotional processing, particularly reducing rumination and boosting positive affect, could have measurable effects on sleep quality in this age group. The study also shows that daily emotional states matter above and beyond stable personality traits, underscoring the value of moment-to-moment emotional regulation for healthy sleep.
Limits
Participants were predominantly female (80.1%) and drawn from psychology programs at two Swiss universities, limiting generalizability. Sleep quality was measured by a single self-report item, not polysomnography or actigraphy. The observational design cannot establish causality, and the association between negative affect and sleep may reflect reverse causation or shared underlying factors such as anxiety disorders.
Bottom line
What you feel during the day carries into your sleep at night. In emerging adults, daily anger, anxiety, sadness, and stress each degrade sleep quality, while happiness protects it. Rumination, repeatedly dwelling on negative thoughts, appears especially detrimental at the habitual level.
Source
Ariu A, Meyer AH, Munsch S, Messerli-Bürgy N. “Dynamic Interactions Between Daily Emotional Processing and Sleep Quality in Emerging Adults.” Journal of Sleep Research, Early View e70406 (2026). DOI: 10.1111/jsr.70406. Open Access (CC BY 4.0).