Sleep related breathing disorders in childhood are increasingly recognised as contributors to morbidity as well as suboptimal physical, mental and social development. The associated cost in social and economic terms is clearly significant. Detection and diagnosis of such disorders can be costly and technically difficult. Multi-parameter monitoring like polysomnography is expensive and inappropriate for mass screening or investigations remote from tertiary centres. A simple and non-invasive cardiovascular approach termed pulse transit time (PTT) is useful in determining the status of upper airways during sleep. This approach employs the measurement of the time delay in the arterial pulse pressure wave from the aortic valve of the heart to a peripheral site. PTT has shown promise to provide quantify inspiratory effort in adults with sleep disordered breathing (SDB) and can then be an effective monitoring tool in children. Initial investigations explore the parameters that can confound the PTT measurements of a child. This work provides an estimate of the expected PTT ranges from infancy to childhood. Thereafter, overnight PTT recordings were performed in conjunction with PSG studies to corroborate evidence for its capability in paediatric respiratory studies. The results show that PTT has the ability to identify abnormal respiratory events during sleep. Furthermore, the use of PTT can differentiate the nature of respiratory events as obstructive or central. Technological considerations to improve the robustness of PTT measure to be used not only in cardiorespiratory but also cardiovascular studies on children were also illustrated. Preliminary findings obtained here suggest that the properties of PTT show promise as a predictor for obstructive sleep apnoea. There is a need to bridge the gap of providing quality SDB diagnosis and yet accommodating requirements for a robust screening measure. PTT has demonstrated its suitability and utility as a measure to play a role in the investigation and monitoring of treatment in this area.

Made available in DSpace on 2014-12-17T15:36:56Z (GMT). No. of bitstreams: 1 AndreLHP_Capa_a_Pag78.pdf: 4907555 bytes, checksum: 6e6da787d601f791eab35a63d8938972 (MD5) Previous issue date: 2009-05-22 / Several lines of evidence indicate that sleep is beneficial for learning, but there is no experimental evidence yet that the content of dreams is adaptive, i.e., that dreams help the dreamer to cope with challenges of the following day. Our aim here is to investigate the role of dreams in the acquisition of a complex cognitive task. We investigated electroencephalographic recordings and dream reports of adult subjects exposed to a computer game comprising perceptual, motor, spatial, emotional and higher-level cognitive aspects (Doom). Subjects slept two nights in the sleep laboratory, a completely dark room with a comfortable bed and controlled temperature. Electroencephalographic recordings with 28 channels were continuously performed throughout the experiment to identify episodes of rapid-eye-movement (REM) sleep. Behaviors were continuously recorded in audio and video with an infrared camera. Dream reports were collected upon forced awakening from late REM sleep, and again in the morning after spontaneous awakening. On day 1, subjects were habituated to the sleep laboratory, no computer game was played, and negative controls for gamerelated dream reports were collected. On day 2, subjects played the computer game before and after sleep. Each game session lasted for an hour, and sleep for 7-9 hours. 9 different measures of performance indicated significant improve overnight. 81% of the subjects experienced intrusion of elements of the game into their dreams, including potentially adaptative strategies (insights). There was a linear correlation between performance and dream intrusion as well as for game improval and quantity of reported dreaming. In the electrophysiological analysis we mapped the subjects brain activities in different stages (SWS 1, REM 1, SWS 2, REM 2, Game 1 and Game 2), and found a modest reverberation in motor areas related to the joystick control during the sleep. When separated by gender, we found a significant difference on female subjects in the channels that indicate motor learning. Analysis of dream reports showed that the amount of gamerelated elements in dreams correlated with performance gains according to an inverted-U function analogous to the Yerkes-Dodson law that governs the relationship between arousal and learning. The results indicate that dreaming is an adaptive behavior / V?rias linhas de pesquisa indicam que o sono ? ben?fico para a aprendizagem, mas ainda n?o h? evid?ncias experimentais de que o conte?do dos sonhos ? adaptativo, isto ?, que os sonhos ajudam o sonhador a lidar com os desafios do dia seguinte. O objetivo deste trabalho ? investigar a rela??o dos sonhos como fator de aprendizagem e adapta??o a uma tarefa cognitiva complexa. Investigamos registros eletroencefalogr?ficos e relatos de sonhos de volunt?rios adultos expostos a um jogo de computador ("Doom") que envolve o aprendizado perceptual, motor, espacial e emocional, al?m de aspectos cognitivos de mais alta ordem ("insights"). Os volunt?rios dormiram duas noites no laborat?rio do sono, uma sala completamente escura com uma cama confort?vel e temperatura controlada. Registros polissonogr?ficos com 28 canais foram continuamente realizados durante todo o experimento para identificar epis?dios de sono REM, durante o qual prevalece a atividade on?rica. O comportamento dos volunt?rios foi continuamente registrado em ?udio e v?deo com uma c?mera infravermelha. Os relatos de sonho foram coletados mediante despertar for?ado de sono REM. No dia 1, os indiv?duos foram habituados ao laborat?rio de sono. No dia 2, os volunt?rios jogaram o jogo no computador antes e depois do sono. Cada sess?o do jogo durou 1 hora, e o sono durou 7-9 horas. Medidas de 9 tipos de desempenho mostraram melhora significativa ap?s uma noite de sono. 81% dos indiv?duos relataram intrus?o de elementos do jogo nos seus sonhos, incluindo estrat?gias potencialmente adaptativas (insight). Vimos uma correla??o linear entre os desempenhos e as intrus?es de elementos do jogo. Na an?lise eletrofisiol?gica do mapeamento cerebral de todos os sujeitos em estados espec?ficos (SWS 1, REM 1, SWS 2, REM 2, Jogo 1 e Jogo 2), verificamos uma modesta reverbera??o em ?reas motoras relacionadas com o controle do joystick durante o sono. Quando separamos os jogadores por sexo, verificamos no grupo de mulheres uma diferen?a significativa em canais que indicam este aprendizado motor. Os resultados indicam que sonhar pode ser um comportamento adaptativo

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