Associations among Sleep, Physical Activity, and Psychosocial Functioning among Emerging Adults at University: An Examination of the Moderating Role of Gender and Athlete Status

Despite extant research on associations among sleep, physical activity, and psychosocial functioning, few studies have explored whether these associations differ by gender and athlete status, specifically within the context of university. The aim of the present study was to examine gender and athlete status as moderators of the relationships among sleep, physical activity, and various indices of psychosocial functioning (e.g., mental health and alcohol use) among emerging adults. Participants were 187 students enrolled at a small, liberal arts university (Mean age = 20.40 years old, SD = 1.80, 65.2% female), who completed an online survey, as part of a larger study on psychosocial adjustment in university. Hierarchical regression analyses, controlling for key covariates such as demographics, mental illness, selfesteem, grit, and chronotype, indicated that athlete status moderated the association between sleep problems and self-esteem. Gender moderated the association between sleep disturbances and stress, as well as sleep disturbances and depression. Furthermore, both gender and athlete status moderated the association between alcohol use and social jetlag (i.e., the misalignment between one’s biological and social clocks). Findings have important implications for both athlete and non-athlete university students, coaches, and university administration by providing insight into how demands of university schedules are linked to sleep-wake timing, patterns of physical activity, and overall psychosocial adjustment during the critical developmental age period of emerging adulthood. RUNNING HEAD: SLEEP, PHYSICAL ACTIVITY, AND PSYCHOSOCIAL FUNCTIONING 1 Associations among Sleep, Physical Activity, and Psychosocial Functioning among Emerging Adults at University: An Examination of the Moderating Role of Gender and Athlete Status Emerging adulthood is a unique and sensitive period of development between adolescence and adulthood, spanning the age range of 18 to 29 years old. Relative to adolescents, emerging adults typically experience increased exploration and independence (e.g., become of legal drinking age and do not have parent-set bedtimes and wake times). Emerging adults also generally experience higher instability in living arrangements and face unique challenges in identity development, establishing and maintaining romantic relationships, and pursuing career goals (Arnett, 2000; Arnett, 2007, Pittman & Richmond, 2008), relative to other age groups. For emerging adults who choose to leave home to attend university, being away from home yields unique challenges, as individuals must balance competing academic and social demands, while adjusting to the university setting. Emerging adults at university, therefore, encounter the salience of social ties with peers as they balance long distance ties with family members and high school friends. These new social ties at university have been linked to important aspects of psychosocial functioning, including more effective emotion regulation and better sleep quality (Tavernier & Willoughby, 2015). Importantly, past research indicates that there are marked changes in sleep characteristics during emerging adulthood. For example, emerging adults at RUNNING HEAD: SLEEP, PHYSICAL ACTIVITY, AND PSYCHOSOCIAL FUNCTIONING 2 university typically compromise sleep during the weekdays and experience significant delayed sleep-wake timing on the weekends, resulting in irregular sleepwake schedules (Orzech et al., 2011). Given the critical role that sleep plays in regulating cognitive and emotional processes that are essential for optimal physical and mental well-being, it is crucial that researchers examine the interplay between sleep and various aspects of psychosocial functioning among emerging adults at university. An important factor that has been shown to be implicated in the link between sleep and overall well-being is physical activity. Physical Activity and Sleep Physical activity refers to any bodily movement produced by skeletal muscles resulting in energy expenditure (e.g., sports, conditioning, and household chores) (Caspersen, Powell, & Christenson, 1985). Exercise, on the other hand, is a subcategory of physical activity that is planned, structured, and repetitive with the goal of improving physical fitness (Caspersen et al., 1985; Kilpatrick, Hebert, & Bartholomew, 2005). Physical activity has been measured in a myriad of ways in past research. While the doubly labeled water method (DLW) is considered the gold standard for assessing total energy expenditure, this method is not typically used because it is expensive, time-consuming, and does not provide qualitative data (Sylvia et al., 2014). Other measures utilized in previous studies include calorimetry, accelerometers, pedometers, heart rate monitors, and armbands – all of which provide an objective assessment of physical activity (Laporte, Montoye, & Caspersen, 1985; Sylvia et al., 2013). Subjective measures of physical activity include self-report RUNNING HEAD: SLEEP, PHYSICAL ACTIVITY, AND PSYCHOSOCIAL FUNCTIONING 3 questionnaires, self-report activity diaries, and direct observation. Self-report instruments are the most common method of measuring physical activity and rely on participants’ recall ability and subjective perceptions (Sylvia et al., 2014). The advantages of utilizing this assessment are its accuracy in measuring intense activity, ranking of individuals of groups by their physical activity, and their ability to collect data from a large sample at relatively low cost. Furthermore, self-reports can be used for a wide range of ages and can be adapted to fit the needs of a particular research study (Sallis & Saelens, 2000; Sylvia et al., 2013). Despite these advantages, however, self-report measures may not always be an accurate account because of their reliance on subjective memory, as individuals tend to overestimate their levels of physical activity (Lang et al., 2013). Sleep is a multi-dimensional construct, comprised of a number of different components, including: sleep duration (the actual number of hours spent sleeping, minus periods of awakening); sleep onset latency (the amount of time between bedtime and sleep onset); sleep efficiency (the proportion of time spent sleeping as a percentage of time in bed); sleep problems/quality (subjective perception of the quality and restfulness of one’s sleep); and night awakenings (total amount of time spent awake between sleep onset and wake time). Within the field, polysomnography remains the gold standard for measuring sleep stages (Rechtschaffen & Kales, 1968). Actigraphy, the assessment of sleep characteristics based on activity levels or movement, however, provides a valid alternative to objective assessments of some sleep characteristics (e.g., sleep duration, sleep efficiency, and night awakenings; RUNNING HEAD: SLEEP, PHYSICAL ACTIVITY, AND PSYCHOSOCIAL FUNCTIONING 4 Sadeh et al., 1994). The majority of studies on sleep and psychosocial adjustment have been based on subjective or self-report assessments of various sleep parameters. The two most commonly used scales are the Pittsburgh Sleep Quality Index (PSQI, Buysse et al., 1989) and the Insomnia Severity Index (ISI, Bastien et al., 2001). Both measures include questions assessing participants’ subjective experience of insomnia symptoms, such as difficulty initiating and maintaining sleep. Within the literature, there is both theoretical and empirical support for a link between sleep and physical activity. Specifically, past research proposes that intensity of physical activity and exercise is positively associated with good sleep hygiene. Brand and colleagues (2014) assessed the relationship between self-perceived exercise exertion before bedtime and objectively measured sleep outcomes. The sample consisted of 52 high school students who regularly participated in sports two to three times a week in the evening for at least 70 consecutive minutes. Participants underwent sleep electroencephalographic recordings 1.5 hours after completing moderate to vigorous exercise in the evening, which provided information about total sleep time, sleep onset latency, and sleep efficiency (Brand et al., 2014). Participants also reported their level of exercise exertion before sleeping, as well as perceived sleep quality (assessed the following morning). Correlational analyses indicated that greater exercise exertion was associated with higher sleep efficiency, fewer night awakenings and better subjective sleep quality (Brand et al., 2014). Lang and colleagues (2013) made an important contribution to the field by employing subjective and objective assessments of both physical activity and sleep RUNNING HEAD: SLEEP, PHYSICAL ACTIVITY, AND PSYCHOSOCIAL FUNCTIONING 5 quality within the same study. Thirty-seven adolescents wore a digital accelerometer, which provided objective data on physical activity. Objective sleep data were based on EEG recordings across three days and nights, which provided assessments of total sleep time and sleep onset latency (Lang et al., 2013). Subjective physical activity and subjective sleep were measured by questionnaires that assessed the frequency (days) of engaging in vigorous physical activity in the previous week, as well as sleep quality and sleep problems. A linear regression model revealed that vigorous physical activity was a better predictor of positive sleep characteristics than moderate physical activity. Specifically, greater levels of subjective and objective vigorous physical activity were associated with shorter sleep onset latencies, longer total sleep time, fewer night awakenings, fewer insomnia symptoms, and better subjective sleep quality. Furthermore, self-reported physical activity level was a better predictor of sleep than objectively measured physical activity, such that participants with greater self-reported physical activity levels had significantly shorter self-r