Sleep duration associated with feelings but not with test scores: an observational study

Abstract Sleep and mood/emotion influence learning and academic achievement. However, inconclusive/contradictory findings have been reported. Unlike previous studies that examined either sleep or mood and grade-point-average (combined result of several assessments over long period), this study examined UK university students for the relationship of test scores with both, previous night’s sleep-duration, and mood/emotion approximately an hour before the test. Mood/feelings data were collected by presenting a selection of emojis and text. Here, test scores did not associate with night sleep-duration. There were no differences in distribution of scores across sleepers of 5, 6, 7 and 8 h and sleeping for less than these hours did not increase the odds of scoring low (scoring ≤ 25%). There was no significant difference in distribution of night-sleep-hours between high scorers (score ≥ 75%) and low scorers (score ≤ 25%). Furthermore, test scores did not associate with feelings/emotions. There were no significant differences in the distribution of scores across different feelings. Unhappy/negative feelings did not increase the odds of scoring low. However, feelings (specifically expressed through selection of words/phrases) predicted scores (p = 0.01) and both negative and positive feelings associated with increased odds of high score (p ≤ 0.04). Night-sleep-duration positively associated with feelings (p < 0.001). Distribution of night-sleep-duration differed between feelings (p ≤ 0.003). Night sleep of less than 5, 6, 7 or 8 h increased the odds of feeling unhappy/negative (p ≤ 0.01). This data (i) defies the generic notion of a night of sub-optimal sleep-duration negatively affecting scores, (ii) provides empirical evidence of association between night-sleep-duration and emotions/mood/feelings, and (iii) proposes that sleep may affect learning via mood.