Lauren Hammond

Eastern Psychological Association Conference

March 2019

Lauren Hammond, Catherine Mello, Matthew Rhudy, Tanya White, & Nathan Greenauer

The Pennsylvania State University, Berks

Short Abstract

The present study examined and compared undergraduate students’ subjective and objective measures of sleep quantity and quality. Data included subjective measures of daytime sleepiness, sleep quality, and duration. The Fitbit Flex 2 wrist-worn activity monitor was used as an objective measure of sleep duration and quality. Overall, participants exhibited patterns of mild sleep deprivation. Subjective and objective sleep quality measures showed positive and negative associations with mental health outcomes, respectively.

Long Abstract

Introduction

Sleep loss has emerged as a national public health concern in recent years. The long-term effects of insufficient sleep include an increased risk for type two diabetes and obesity (Knuston et al., 2007). Additionally, the short-term effects of poor sleep include cognitive (e.g., concentration, memory) impairments and emotional difficulties. Undergraduate students may be particularly susceptible to insufficient sleep, in quantity and quality, often as a result of struggling to balance work, school, and social demands (Barone, 2017). Maintaining a consistent nocturnal sleep schedule is believed to help young adults attain optimal functioning in terms of mood and performance (Taub, 1978). It is typically recommended that adults aged 18 to 24 years get at least seven to nine hours of sleep on a nightly basis. The National Sleep Foundation warns against poor sleep schedules that are below six hours or in excess of 11 hours (2015). A concern for academic performance may prompt students to curtail their sleep or modify their sleep schedule in favor of perceived immediate benefits (e.g., meeting a deadline or cramming) despite the fact that it could be detrimental to their immediate performance and have longer-term consequences on their academic success.  Indeed, undergraduate students often report that sleep is of minimal importance in their daily life and that sleep loss is simply a part of their everyday lifestyle (Coveney, 2014). Yet, poor sleep habits are associated with poorer academic performance and negative health outcomes in college students (Barone, 2017).

Methods

Twenty undergraduate students (15 female, 5 male) wore a Fitbit Flex 2 wrist-worn activity monitor to track their physical activity and sleep during the first four days of the weekdays for a total of three consecutive weeks. Additionally, participants completed a self-report daily survey throughout the study along with a weekly survey. The daily survey consisted of a measure of daily mood (positive and negative emotions), a measure of subjective sleep quality (adapted from the Karolinska Sleep Diary; Akerstedt et al., 1994) and subjective vitality (Ryan et al., 2010). The weekly survey included a combination of pre-existing measures: the Pittsburgh Sleep Quality Index (Buysse et al., 1989), the Epworth Sleepiness Scale (Johns, 1991), and the Positive and Negative Affect Schedule (Watson et al., 1988). In addition to these measures, participants were asked at intake to estimate their typical sleep duration.  The Fitbit provided an objective measure of sleep quality (% of time in bed spent asleep) and duration.

Results

At intake, participants reported that they slept an average of 6.8 hours (SD = 1.6) each night while Fitbit mean sleep duration was 7.3 (SD = 1.4) hours, which was significantly less than the recommended 8 hours, t(115) = 46.604, p < .001. Participants only met the eight-hour standard sleep recommendation on 22.5% percent, but exceeded it on 32.5%, of recorded nights. Twenty-five percent of participants reported they always or very frequently have trouble falling asleep at night, while twenty-five percent of participants also reported having trouble staying asleep very frequently or always. According to the Epworth Sleepiness Scale, 11.1 and 4.4% of participants reported moderate or severe daytime sleepiness, respectively. On a daily basis, only 3.1% of participants reported feeling refreshed after waking while 18.4% percent reported not feeling refreshed at all. Reports of difficulties in waking up were fairly common (25.2%).

Students’ sleep quality and quantity presented several associations with affective and hedonic measures. Sleeping longer on a given night was associated with lower subjective sleep quality ratings for that night, r(102) = -.234, p = .017. Additionally, weekly reports of daytime sleepiness were positively correlated with weekly negative affect, r(18) = .548, p = .012. Over the full duration of the study, participants’ average, objective sleep quantity and quality as measured by the Fitbit, correlated positively with their average levels of negative emotion, r(8) = .859, p = .001 and r(8) = .679, p = .031. In contrast, subjective sleep quality was positively correlated with subjective vitality, r(8) = .669, p = .001.

Discussion

This present study evaluated subjective and objective sleep quantity and quality, as well as the correspondence between the two. Objective sleep measured through the FitBit Flex 2 wrist-worn monitor indicated that participants received more sleep than they estimated was typical of them. Total recommended sleep quantities range between seven and nine hours of sleep for young adults, yet participants were at the lower end of this range as a group even by objective sleep measures. Thus, our results are consistent with findings of insufficient sleep among students due to balancing their day to day workloads in pressured environments like school, jobs, or both (National Sleep Foundation, 2015). Intriguingly, while subjective sleep deprivation (sleepiness, poor sleep quality) was associated with lower affect and vitality, objective sleep quantity and quality both seemed associated with negative outcomes. These findings will be examined in the context of other daytime activities that may account for sleep patterns and mental health outcomes.

References

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