Bibliography: leaves 242-268 / viii, 268 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Quantifies the effects of sleep deprivation on performance, validates methods of objectively measuring the sleep-wake activity of shiftworkers and investigates the effects of shiftwork on both sleep and performance in the laboratory and the field. Shows that actigraphy is a valid and reliable method of determining sleep-wake in shiftworkers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1999

Bibliography: leaves 242-268 / viii, 268 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Quantifies the effects of sleep deprivation on performance, validates methods of objectively measuring the sleep-wake activity of shiftworkers and investigates the effects of shiftwork on both sleep and performance in the laboratory and the field. Shows that actigraphy is a valid and reliable method of determining sleep-wake in shiftworkers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1999

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M.S.)--University of Michigan, 1980.

Thesis (M.S.)--Oregon State University, 2004. / Includes bibliographical references. Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.S.)--University of Michigan, 1980.

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M.S.)--Oregon State University, 2004. / Includes bibliographical references.

The daily sleep-wake cycle usually consists of three distinct states: wakefulness, non-rapid-eye-movement (NREM) and rapid-eye-movement (REM). The process of switching between different states is complex, but a common assumption is that it is regulated primarily by two processes (the circadian and the homeostatic process) via reciprocal interactions of several downstream neuron groups. These interactions not only result in often rapid transitions from one state to another, but also allow for a certain degree of bi-stability that locks the organism in a given state for some while before it switches back. In order to better understand how the behavioral states are regulated by different neuron groups, I describe how to use the S-system method for the development of a mathematical model consisting of two phases. The first phase covers the switch between wakefulness and sleep, which is controlled by the interactions between wake- and sleep-promoting neurons, whereas the second phase addresses the generation of NREM-REM alternation, which is believed to be regulated by REM-OFF and REM-ON neurons. In this set-up I interpret the circadian rhythm as external input and homeostatic regulation as a feedback controller. Both open-loop and closed-loop forms of the two-phase model are investigated and implemented. Discharging activities of the corresponding neuron groups and the switches of behavioral states are shown in the simulation results, from which we can easily identify the basic roles of wake- and sleep-promoting neurons, REM-OFF and REM-ON neurons. The special regulatory function of the neuropeptide orexin is also tested by simulation.

Introdução - A sonolência é descrita como a interação entre o momento circadiano para adormecer e o aumento da necessidade de sono, e está em geral, associada ao decréscimo do alerta, do tempo de reação, da memória, da coordenação psicomotora, do entendimento da informação, do tempo para se tomar decisões, da maior incidência de uso de substâncias estimulantes e de substâncias álcoolicas. Na adolescência, a sonolência limita as perspectivas dos adolescentes quanto ao seu desenvolvimento intelectual. Muito pouco se conhece sobre a percepção da sonolência em estudantes trabalhadores. Objetivo - Verificar variações da sonolência ao longo do dia e o possível impacto das atividades diárias e estilos de vida na sonolência em estudantes. Metodologia - A população estudada compreendem estudantes trabalhadores e não-trabalhadores, alunos do ensino médio do período noturno de uma escola pública estadual da cidade de São Paulo, SP. Participaram estudantes entre 14 e 21 anos de idade incompletos. Os estudantes selecionados preencheram os questionários de: caracterização das condições de vida, saúde e sono, matutinidade-vespertinidade, caracterização das condições de trabalho e freqüência alimentar. Em seguida foi realizada a obtenção de registros sobre o ciclo vigília-sono dos estudantes através de métodos subjetivos (Protocolo diário de atividades, diário de sono e escala de sonolência) e objetivos (Actimetria). As variáveis sócio-demográficas, estilos de vida, condições de trabalho e do ciclo vigília-sono foram testadas através do teste t-Student, ANOVA para três fatores (dia da semana, horário e trabalho), Qui-Quadrado de Pearson (c2) e análise de regressão. Resultados - 1) a duração média do sono nos dias da semana para os estudantes trabalhadores foi em torno de 7h, enquanto a duração do sono dos estudantes não trabalhadores foi em torno de 9h; 2) os padrões de sonolência de estudantes trabalhadores são diferentes dos estudantes não-trabalhadores. Verificamos que os estudantes trabalhadores são mais sonolentos que os estudantes não-trabalhadores no primeiro registro diário (07├ 09 h) e no último (22├ 24 h). Verificamos que os estudantes trabalhadores são mais sonolentos que estudantes não-trabalhadores na segunda-feira após o almoço (13├ 15 h), na quarta-feira durante as aulas (19├ 21 h) e na sexta-feira antes de dormir (22├ 24 h). Aos domingos, entre 22├ 24 h foi encontrada o maior nível de sonolência entre os estudantes trabalhadores. Também, neste momento, os trabalhadores são mais sonolentos que os estudantes não-trabalhadores em todos os outros dias e horários; 3) os fatores independentemente associados a estar sonolento foram: trabalhar, ser do sexo feminino, consumir álcool, ter maior dificuldade para adormecer e ir dormir após as 24h. Conclusões - Os padrões de sonolência de estudantes trabalhadores são diferentes dos estudantes não-trabalhadores e as variáveis do ciclo vigília-sono interferem nos níveis de sonolência ao longo do dia. Além dos fatores cronobiológicos outros fatores estão relacionados às mudanças nos níveis da sonolência: a) fatores individuais; b) fatores sociais; c) fatores sócio-demográficos e d) estilos de vida. Essa gama de fatores acaba levando ao aumento da sonolência no início e fim do dia para os estudantes trabalhadores, podendo interferir no rendimento escolar e prejudicar o desenvolvimento físico e mental, característicos da adolescência. Programas de intervenção tais como, o conhecimento sobre a higiene do sono e as políticas de inserção social que permitam aos estudantes manter um padrão de vida adequado sem ter que sujeitar a longas jornadas de trabalho enquanto na adolescência, devem ser implementados. / Introduction – Sleepiness is described as an interaction between the circadian phase and the increase in pressure to sleep. In general, it is associated with a decrease in alertness levels, reaction time, memory, psychomotor coordination, information assimilation, time to take decisions, and larger consumption of stimulant and alcoholic substances. In adolescence, sleepiness restricts the adolescent’s perspectives as to his/her intellectual development. Knowledge on perception of sleepiness in working students is poor. Objective – Verifying patterns of sleepiness along the day and the possible impact of daily activities and life styles on sleepiness among working and non-working students. Methods – The population studied comprised working and non-working high school students attending evening classes (19:00-22.30pm) at a public school in São Paulo, Brazil. The study group consisted of working and non-working students aged 14-21. The students selected filled in a questionnaire on living conditions, health and sleep, morningness-eveningness, characterization of working conditions, and frequency of food consumption. As a second step, records of their sleep-wake cycle were obtained through subjective methods (daily protocol of activities, sleep diary and sleepiness scale), as well as objective methods (Actigraphy). Socio-demographic, life style, work conditions and sleep-wake cycle variables were tested with the use of three-way ANOVA test (week day, time and work), Person’s Qui-Square test (c2) and regression analysis. Results - 1) The average sleep duration for working students during weekdays was around 7 hours, whereas the sleep duration for non-working students was around 9 hours; 2) working students’ sleepiness patterns are different from those of non-working students. We found that working students were sleepier than non-working students in the first period (07:00am-09:00am) and in the last period recorded (10:00pm-12:00pm). We also found that working students were sleepier on specific days: on Mondays after lunch time (01:00pm-03:00pm), on Wednesdays during classes (07:00pm-09:00pm) and on Fridays before bedtime (10:00pm-12:00pm). The highest level of sleepiness among students was found on Sundays, between 10:00pm-12:00pm. Also, at this time period working students in general were sleepier than non-working students, independently of the period and time of the day. 3) Other factors associated with sleepiness were: work, being a female, alcohol consumption, easiness of sleeping and going to bed after midnight. Conclusions – The sleepiness patterns for working students are different from those for non-working students, and the sleep-wake cycle variables interfere in sleepiness levels during the day. In addition to chronobiological factors, there are other factors associated with changes in sleepiness levels: a) individual factors; b) social factors; c) socio-demographic factors; and d) life style. All these factors contribute to increase in working students’ sleepiness at the beginning and end of the day; this may interfere in their school performance, impairing their physical and mental development, which is characteristic of adolescence. Intervention programs, such as those that provide information on sleep hygiene, and those related to social insertion, which would allow students to maintain and adequate life standard without having to be submitted to extended work journeys, should be implemented.