Introduction: While experimental sleep restriction data showed altered frontal lobe activation and risk-taking tendency among youths, we investigated if naturalistic sleep patterns were also related to youth’s executive functions, including planning and risk-taking. Methods: A convenient sample of college students (N=194) completed a sleep diary and wore an actigraph-watch for 5 days to measure their average and variability (standard deviation, SD) of total-sleeptime and mid-sleep-time. Sleep restriction referred to less than 6 hours of sleep with reference to the National Sleep Foundation. Participants also completed the Pittsburgh Sleep Quality Index (PSQI) and Composite Scale of Morningness (CSM). On the 6th day, they completed the Tower of London and Risky-gain Task at 1-2pm as measures of their planning and risk-taking, respectively. Results: The sample had a mean total-sleep-time of 7.1h (SD=1.1h) on sleep diary and 7.4h (SD=1.0h) on actigraphy, PSQI of 6.4 (SD=2.4) and CSM of 29.2 (SD=5.6). Correlational analyses showed that selection of risky choices following punishment trials was related to variability of mid-sleep-time (actigraphy, r=.160, p=.038, and sleep diary, r=.202, p=.033), apart from higher PSQI, p=.157, p=.032, and lower CSM (eveningness), r=-.173, p=.019. Number of steps in completing the Tower of London task was correlated with lower alertness after wake-up in the morning (CSM subscale), r=-.172, p=.017. Totalsleep-time and its variability were not correlated with risk-taking or planning. Independent t-test showed youths with or without habitual sleep restriction did not differ on measures of risk-taking or planning. Conclusion: Contrary to experimental data on sleep restriction, here we showed that planning and risk-taking were correlated with sleep timing variability, sleep quality and chronotype, but not habitual total sleep duration or its variability. While decreasing sleep duration is a general phenomenon among youths, sleep education should also promote regularity of sleep timing to optimize youth’s cognitive functioning. Support (If Any): Funder: General Research Fund (#17612015), Research Grant Councils, HKSAR.
|Publication status||Published - Jun 2017|