ABSTRACT:Context: The precise function of sleep in animals and human beings is still unknown, and any sort of physical, social or psychological variation may change the normal sleep-wake cycle. Purpose: This research aims is to determine the sleep disorders (SD) for each of the three trimesters of the pregnancy comparing them to the pre-pregnancy state (PG). Method: SD were investigated in three hundred pregnant women 11-to 40-years-old through with a brief clinical interview based on directed questions. One hundred pregnant women were considered for each trimester. Results: The rate of pregnant women with insomnia increased by 23% in the 2 nd trimester (p< 0.005); the rate for excessive daytime sleepiness (EDS) by 15% in the 1 st trimester (p<0.003), 55% in the 2 nd trimester (p<0.001) and by 14% in the 3 rd trimester (p<0.002); the rate for mild sleepiness increased by 33% in the 2 nd trimester (p<0.002) and by 48% in the 3 rd trimester (p<0.001); the rate for specific awakenings increased by 63% in the 1 st trimester, by 80% in the 2 nd trimester and by 84% in the 3 rd trimester (p<0.001). Conclusion: SD were more frequent during pregnancy comparatively to PG state, mostly at the expenses of EDS and specific awakenings.KEY WORDS: pregnancy, sleep disorders, awakening, insomnia, excessive daytime sleepiness. Distúrbios do sono na gravidezRESUMO -Introdução: A função exata do sono em animais e seres humanos ainda é desconhecida e qualquer variação física, social ou psíquica pode alterar o ciclo normal de sono e vigília. Objetivo: O objetivo desta pesquisa é detectar os principais distúrbios do sono (DS) nos três trimestres da gravidez comparando-os ao estado pré-gestacional (PG). Método: Os DS foram investigados em 300 gestantes com idades variando de 11 a 40 anos, através de breve entrevista com questões dirigidas. Foram incluídas 100 gestantes para cada trimestre. Resultados: A proporção de grávidas com insônia aumentou 23% no 2º trimestre (p<0,005); a de sonolência intensa 15% no 1º trimestre (p<0,003), 55% no 2º (p<0,001) e 14% no 3º (p<0,002); a de sonolência leve 33% no 2º trimestre (p<0,002) e 48% no 3º (p<0,001); a de despertares específicos 63% no 1º trimestre, 80% no 2º e 84% no 3º (p<0,001). Conclusão: DS foram mais freqüentes durante a gravidez comparativamente ao PG, principalmente às custas de sonolência intensa e despertares específicos. PALAVRAS-CHAVE: gravidez, distúrbios do sono, despertar, insônia, sonolência excessiva diurna.It is not known the precise function of sleep in animals and human beings. The main explanation considers the need to replenish individual's energy (physical and psychological).The restoration provided by sleep seems to be an important component, once it is preceded by fatigue and usually followed by feelings of satisfaction.When there is an impossibility to sleep well, restrictions in day functioning or excessive daytime sleepiness (EDS) may occur 1-2 . Physical, emotional and social variations in human beings' life may induce sleep disorders as insomnia and EDS. The gr...