Research suggests that elevated levels of screen time in the evening can negatively impact sleep outcomes (sleep duration, quality, and latency). Yet, there is a lack of evidence exploring if this relationship exists in college students. The purpose of this study is to investigate the relationship between evening screen time use and objectively measured sleep outcomes in US college students. College students (N = 29) junior or senior standing in a Health Sciences major were recruited to participate in this cross-sectional study. Participants wore accelerometers on their wrist for 24hr/day for seven days to capture sleep duration, efficiency, awakenings, and timing. Participants completed a survey regarding their screen time habits and evening usage. Twenty-nine college students (86% female, averaged 21.5 years old, 38% White, 35% Overweight/Obese) provided valid accelerometer data. There were 180 total valid night sleep observations. Average nighttime sleep duration was 433.8 minutes with an average of 22.3 awakenings. The mean sleep efficiency was 87.3%. The average bedtime was 2:26 am, and the average wake time was 8:01 am. The average daily screen time of participants was 419.1 minutes, and after 10:00 pm was 112.2 minutes. Cell phone use before bed was negatively correlated with self-reported sleep duration (r = -0.42; p-value = 0.02), and positively correlated with stimulating screen time content (r = 0.43; p-value = 0.02). Those who napped had a lower daily screen time duration compared to those who did not nap (Mean difference = 91.7 minutes; p-value = 0.05) and had a higher sleep efficiency of 95.8%. Preliminary evidence suggests that a relationship between both evening screen time duration in addition to content, and objectively measured sleep outcomes may exist for US college students. This study provides reliable, objective data of college student sleep that may inform future public health interventions in this population.

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Researchers have struggled with the problem of obtaining an "accurate" operational definition of drowsiness. Drowsiness is difficult to define because it may involve many different indicators, such as different physiological measures. This thesis consists of two separate, but related, experiments to determine an optimal method of determining whether or not an individual is drowsy via physiological and observed measures. The first part of the experiment used behaviorally trained observers to rate different subjects on the level of drowsiness observed. The data collected showed that trained raters are relatively consistent when rating drowsiness. The second part of the experiment tried to determine if there is a good physiological model to predict performance impairment due to drowsiness by collecting data on sleep deprived subjects. The subjects were given two interleaved tasks, low level and high level cognitive tasks, to perform while twenty-one performance and behavioral measures were collected. The results show that a regression model can be developed using eyelid closure measures, simple EEG measures and simple heart-rate measures to predict performance impairment due to drowsiness. / Master of Science

An electronically-controlled positive-displacement bellows-type air pump has been developed in the Bio-medical Engineering Laboratory for the treatment of adult Sleep Apnea Syndrome (SAS). An electronically-controlled positive-displacement pump has been employed in order to eliminate the pressure regulator and accompanying noise of present therapeutic devices. The positive-displacement pump is found to quietly and effectively provide the required airway pressures for the treatment of adult Sleep Apnea Syndrome. New developments in the reduction of the size and noise levels of current therapeutic devices, however, preclude mass production of the bellows-type pump because of its size disadvantage. The custom nasal mask and exhalation valve, control system, pressure-monitoring alarm system, and the controlled humidifier of the positive-displacement pump should be incorporated within the present fanâ type Nasal Continuous Positive Airway Pressure (NCPAP) system to provide quieter, more comfortable, and safer NCPAP therapy. Before the design and development of the positive displacement NCPAP pump is detailed in this thesis, however, the problem of adult Sleep Apnea Syndrome is introduced, available therapies are investigated, and the current NCPAP therapy system is examined. / Master of Science

The current study aimed to examine the naturalistic relationship between physical activity and sleep by exploring frequency, type, and timing of exercise and their association with a variety of sleep variables (e.g., sleep onset latency, wake after sleep onset, sleep efficiency). Young adults (n = 1003) completed a variety of self-report questionnaires, including a week-long sleep diary and a survey of typical frequency, type, and timing of exercise completed in the past week. Increased frequency of physical activity was related to increased sleep efficiency (total sleep time/time in bed), decreased time in bed, and decreased time spent awake in bed in the morning. Greater amounts of exercise energy expenditure (i.e., metabolic equivalents) per week was related to increased sleep efficiency, and decreased time in bed and time spent awake in bed in the morning. After controlling for other factors, this relationship remained true only for time spent awake in bed in the morning. Early morning exercisers reported shorter total sleep time and time in bed than those who typically exercised at other times. No exercise differences were found between those who met the research diagnostic criteria for insomnia and those who did not. This study provides valuable information to help guide future experimental and intervention studies.

Both sleep diaries and actigraphy have been recommended to assess sleep in research and clinical settings. Investigators have traditionally used sleep diaries that were completed daily by participants and collected weekly but have recently begun using sleep diaries that are both completed and collected daily. No research had previously assessed the agreement between daily-collected sleep diaries and actigraph data over one week. Undergraduate students were randomly assigned to use daily- or weekly-collected sleep diaries. Sleep parameters obtained from these measures were compared to each other via concordance with concurrent actigraph data. It was hypothesized that daily-collected sleep diaries would have greater concordance with actigraphy than weekly-collected sleep diaries. Results indicated that daily-collected sleep diaries provided more reliable data than weekly-collected sleep diaries, but the differences were not statistically significant. Additional aims examined self-reported sleep diary adherence, the participation day number, and day of the week. There were trends for the Daily group to have better adherence. Overall concordance did not change based on the day number or day of the week. Both sleep diaries yield comparable sleep parameter data, suggesting that clinicians and researchers can use either method to estimate sleep parameters.

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