Analysis of the prevalence of insomnia in the adult population of São José do Rio Preto, Brazil.

OBJECTIVE To establish the prevalence of insomnia in the adult urban population of São José do Rio Preto, Brazil and correlate it with the demographic data. METHOD We evaluated 1105 individuals in to guarantee an error margin of 3% and a confidence level of 95% using a structured questionnaire and following the DSM-IV and DSM-III-R criteria, in the period from January 10 to February 28 2001. RESULTS We encountered a prevalence of 32% of insomnia, which was most commonly seen in women, single people, from the lower economical brackets, with a low level of schooling and it was less associated with younger adults (18-31 year-olds). CONCLUSION Our findings indicate that the prevalence of insomnia in the adult population of São José do Rio Preto is comparable with other countries such as the USA and those of Europe and also with other cities in Brazil.