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Many students self-report that they are “night owls,” which can result from neurodevelopmental delays in the circadian timing system. However, whether an individual considers themselves to be an evening-type versus a morning-type (self-reported chronotype) may also be influenced by academic demands (e.g. class start times, course load) and behavioral habits (e.g. bedtime social media use, late caffeine consumption, daytime napping). If so, then chronotype should be malleable. We surveyed 858 undergraduate students enrolled in demanding science courses at up to three time points. The survey assessed morning/evening chronotype, global sleep quality, academics, and behavioral habits. Evening and morning-type students showed similar demographics, stress levels, and academic demands. At baseline measurements, relative to morning-types, evening-types showed significantly worse sleep quality and duration as well as 22% greater bedtime social media usage, 27% greater daytime napping duration, and 46% greater likelihood of consuming caffeine after 5pm. These behavioral habits partially mediated the effects of selfreported chronotype on sleep quality/duration, even after controlling for demographic factors. Interestingly, 54 students reported switching from being at least moderate evening-types at baseline to being at least moderate morning-types later in the semester and 56 students showed the reverse pattern (6.3% of students switched from “definitely” one chronotype to the other chronotype). Evening-to-morning “chrono-switchers” consumed less caffeine after 5pm and showed significantly better sleep quantity/quality at the later timepoint. Thus, some students may consider themselves to be night owls in part because they consume caffeine later, take more daytime naps, or use more social media at bedtime. Experimental work is needed to determine whether nudging night owls to behave like morning larks results in better sleep health or academic achievement.
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For Whom (and When) the Time Bell Tolls: Chronotypes and the Synchrony Effect
Circadian rhythms are powerful timekeepers that drive physiological and intellectual functioning throughout the day. These rhythms vary across individuals, with morning chronotypes rising and peaking early in the day and evening chronotypes showing a later rise in arousal, with peaks in the afternoon or evening. Chronotype also varies with age from childhood to adolescence to old age. As a result of these differences, the time of day at which people are best at attending, learning, solving analytical problems, making complex decisions, and even behaving ethically varies. Across studies of attention and memory and a range of allied areas, including academic achievement, judgment and decision-making, and neuropsychological assessment, optimal outcomes are found when performance times align with peaks in circadian arousal, a finding known as the synchrony effect. The benefits of performing in synchrony with one’s chronotype (and the costs of not doing so) are most robust for individuals with strong morning or evening chronotypes and for tasks that require effortful, analytical processing or the suppression of distracting information. Failure to take the synchrony effect into consideration may be a factor in issues ranging from replication difficulties to school timing to assessing intellectual disabilities and apparent cognitive decline in aging.
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- Award ID(s):
- 1848972
- PAR ID:
- 10426303
- Publisher / Repository:
- SAGE Publications
- Date Published:
- Journal Name:
- Perspectives on Psychological Science
- Volume:
- 18
- Issue:
- 6
- ISSN:
- 1745-6916
- Format(s):
- Medium: X Size: p. 1520-1536
- Size(s):
- p. 1520-1536
- Sponsoring Org:
- National Science Foundation
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