We showed that among a probabilistic sample, female gender, age ≥40 years, insomnia, and OSA were significantly associated with an increased number of hospitalizations and/or demand for emergency services during a short EPISONO follow-up period. Our sample included individuals from the general population and represents the inhabitants of the city of São Paulo between 20 and 80 years of age. In contrast to clinical populations, we evaluated individuals who are much less likely to receive a proper diagnosis or treatment of their sleep disorder.
A recent review by Ohayon suggests that the prevalence of insomnia was already high two decades ago, affecting at least one-third of the population who in most cases, did not receive a proper diagnosis or proper treatment for their condition 
. Studies on the economic impact of insomnia usually discuss direct costs related to resource consumption (i.e., consultations, exams, and products) and indirect costs related to loss (i.e., accidents, absenteeism, and decreased productivity). One recent study showed that insomniacs were 6.7 times more likely to have required medical treatment 
. Even though severe insomnia is directly associated with the use of healthcare services, worldwide quantification of costs is scarce 
. Nonetheless, the costs of untreated insomnia are significantly higher than the direct costs of its treatment 
. Increasing awareness of the efficacy and availability of insomnia treatment, among both patients and health care providers, can greatly reduce its impact and total costs for society.
The prevalence of OSA syndrome in the EPISONO cohort is one of the highest ever found (32.9%) 
. It is important to note that in contrast to most studies, we define this syndrome according to the most recent criteria described by the International Classification of Sleep Disorders (ICSD-2) of the American Academy of Sleep Medicine 
. OSA is a potential predictor of comorbidity and mortality 
, and also has a substantial economic and social impact. Automobile accidents related to OSA in 2000 are estimated to cost $16 billion 
. Even after controlling for confounders, leaving patients untreated generates costs twice as high providing treatment 
. In the US, the annual costs of treating the medical consequences of OSA are estimated to be $3.4 billion 
, even though almost 90% of OSA cases are underdiagnosed 
, especially in populations at lower risk for the disease, such as non-obese women 
, as also suggested by our study.
A recent study showed that among US adults who participated in the National Health and Nutrition Examination Survey, those who reported sleep complaints also had increased healthcare utilization. This study also suggested that sleep disorders appear to be highly underdiagnosed 
Interesting enough, our study showed that moderate and severe AHI could be a factor in association to other clinical conditions, which together, figured as predictor of poor health outcome, while the AHI between 5 and 15, with or without symptoms, was not found to be a risk factor associated with poor health outcome. In addition, more than ¼ of the causes of hospitalizations and/or demand for emergency services during the short follow-up period were linked to cardiovascular disease, as described in previous studies evaluating OSA and even insomnia 
Sao Paulo no doubt represents the worldwide trend of increasing levels of obesity (22%), OSA, insomnia, hypertension, and diabetes (among other diseases) in all metropolitan areas. It seems logical to think that promoting good sleep would regulate some metabolic and functional processes and might also treat some of the other conditions described herein.
We must put forth an effort to recognize sleep disorders and also to raise awareness of the need to educate both physicians and the population about sleep, the diagnosis of sleep disorders, the benefit of behavioral and psychological treatments and interventions, and alternatives to pharmacology in individuals with chronic insomnia and/or a comorbid psychiatric disorder. Additionally, we must understand the potential therapeutic effects on obesity and adherence to nasal Continuous Positive Airway Pressure or to oral appliance treatments, which can to help us to treat OSA and other breathing-related sleep disorders.