A revolution in sleep studies

32.9% of the public has sleep apnea. This was the conclusion of a study on sleep apnea prevalence by Professor Sergio Tufik, which was derived from EPISONO and published in the magazine Sleep Medicine in May 2010. The findings caused a revolution in the methods used to evaluate and understand data on this sleep disorder. Until then, the internationally certified prevalence was that 2% to 4% of the population suffered from obstructive sleep apnea.

EPISONO is an important research project carried out once every decade to check sleep quality and the impact of sleep disorders on the health of a representative sample of the population of the city of São Paulo. It provides important data on the topic for scientific progress, while improving people’s quality of life.

The first three editions of EPISONO, from 1986 to 2007, found that over 60% of the São Paulo population suffers from sleep disorders.

After the article was published, researchers from other countries replicated the study, verifying the numbers revealed by the Sleep Institute and consolidating these results.

EPISONO data showed that:

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EPISONO editions

1986-87 and 1995

The first EPISONO studies provided a representative panorama of the sleep of the São Paulo citizen, demonstrating it as a matter of relevance from the perspective of public health. Complaints about the difficulty in initiating and maintaining sleep, snoring, sleepwalking and insomnia were sleep disorders registered with prevalence.


In this edition, the 1,042 volunteers performed the same procedures as before, in addition to polysomnography, actigraphy and biochemical tests. The results revealed the prevalence of obstructive sleep apnea in 32.9% of the population, insomnia in 15% and bruxism in 7.4%, among other data. Important results also addressed the relationship between sleep and menopause, depression, metabolic syndrome, cardiovascular risk, erectile dysfunction and night headache, among others. It was the first and only study to take patients to sleep in the sleep laboratory considering a representative sample of the city.


All volunteers in the 2007 study were recalled for an assessment of how sleep patterns and the prevalence of sleep disorders evolved over 8 years. As main results, there was a significant increase in sleep apnea rates, especially when associated with weight gain.


To represent the sleep of the population of São Paulo every decade, a new study was conducted between 2018 and 2019, with almost a thousand new volunteers. In addition to the tests previously performed, the participants underwent spirometry tests, a 24-hour electrocardiogram Holter, ambulatory blood pressure monitoring (MAPA), among others.

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