Overview

• The peer-reviewed PLOS One paper, published August 27, 2025, analyzed a cross-sectional survey (n=1,032) and two daily diary studies (n=818; n=236) of 17–25-year-olds in New Zealand, the United Kingdom, and the United States.
• Sleep quality emerged as the strongest and most consistent correlate of psychological well-being across all three datasets.
• Fruit and vegetable consumption was the second-strongest correlate and showed a within-person buffering effect that reduced the well-being dip after poorer sleep.
• Physical activity was linked to better well-being primarily at the day-to-day level, and Fitbit-based activity measures aligned with diary reports.
• Researchers emphasized the observational nature of the findings and urged larger, more diverse, and experimental studies, noting that modest, achievable behavior changes were associated with same-day improvements.