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

The theoretical part of the diploma thesis deals with the effects of sleep on human health. Lack of sleep has demonstrable effects on a person's physical and mental health. People are succumbing to strong influences of present day society, which degrade their quality of sleep. These influences do not only effect adults, but children and adolescents as well. One can improve sleep quality by following sleep hygiene rules. Nowadays these rules are often violated. The main problem is ignorance. The aim of the practical part of this diploma thesis was to compare satisfaction with quality of sleep between groups of students in elementary schools, students of secondary schools, and adult working people. It was also investigated whether respondents in schools were familiar with sleep hygiene and whether they followed it. The results of the questionnaire surveys found that the group least satisfied with sleep quality was the group with working adults. More than half of the respondents in schools were unaware of sleep hygiene. It was confirmed that more than two thirds of respondents do not follow sleep hygiene rules. In the conclusion, the author has included material on sleep problems for grade eight students of elementary schools. It could be used as a draft chaper for future school textbooks, because...