br Material and methods br Discussion Compared to the last
Material and methods
Discussion Compared to the last national survey performed in 2008 , an apparent increase of 13% was observed in the frequency of sleep complaints after 4 years, corresponding approximately to an incidence of 29 million Brazilian inhabitants. However, due mainly to the differences in the quantity of screening questions about sleep problems presented for the subjects in the 2 surveys (5 versus 15 items), we cannot appropriately compare these results. Therefore, this DNA Damage DNA Repair Library may explain why the overall prevalence of sleep problems was higher, although the prevalence estimates for insomnia, snoring, nightmares, kicking legs and breathing pauses were lower in the current study compared to the last one . In agreement with many studies [6,7,34], sleep complaints increased with age and were more prevalent in individuals within 35–44 years, which corresponds to the most economically active group in the current society. Moreover, we found that gender affected sleep, as women reported more sleep problems than men. Grandner and colleagues  also demonstrated more sleep problems in women, but in this study the authors showed that people between the ages of 18 and 24 years reported more sleep complaints than older people. Although sleep complaints generally increased with age, some sleep complaints such as sleep talking, excessive daytime sleepiness, nightmares and somnambulism were more prevalent in younger (16–24 years) than older subjects. The prevalence of insomnia complaint in the current study was high (21%), more frequent in women (24%) and older subjects (30%), according to other studies [6,8,17,19,20,27,38]. In contrast, a recent study revealed a low prevalence of 5.7% for insomnia in Germany . In this study, women were twice as likely to be affected by insomnia as men, but no significant age differences were observed. Additionally, persons with low socioeconomic status had 3 times greater risk of insomnia . Our study also showed the influence of socioeconomics on the prevalence of insomnia complaint, since the majority of people with insomnia complaint had lower educational level (<8 years) and lower income. Indeed, a study by Lalluka and colleagues (2010) demonstrated that past and present economic difficulties were strongly associated with current complaints of insomnia. Also, some evidence has shown that individuals with fewer years of schooling experience greater subjective impairment because of their insomnia , and unemployment or socioeconomic deprivation are strongly associated with insomnia symptoms . In the current study, working people complained more about insomnia than those not working, possibly due to higher levels of stress. In contrast, a recent study showed that subjective insomnia was associated with non-working people with lower education levels . Snoring was the second more frequent sleep complaint after light sleep, with a prevalence of 25%, being significantly higher in subjects older than 45 years old (34%) and men, in agreement with the previous literature [3,7,6,28,37]. As expected, reports of breathing pauses were not frequent (3%) in the population, since they are more commonly reported by partners . However, they were associated with snoring complaints due to its relationship with obstructive sleep apnea. In general, snoring was more prevalent in subjects with higher income (32%). However, Tufik and colleagues (2010) demonstrated that only in men, obstructive sleep apnea is associated with high socioeconomic status, while in women it is associated with lower income. Although compared with the first national survey  no increase was observed in snoring prevalence, Peppard et al.  found an increase of approximately 14% in the prevalence of respiratory sleep disorders in the past 2 decades. We found a 7% prevalence of bruxism in the Brazilian population, which is in line with previous studies [24,29]. In the current study, women (8%) were more affected than men (5%), as already shown by others [1,26]. However, in a representative sample of São Paulo, Maluly and colleagues (2013) demonstrated no significant differences in bruxism prevalence between genders. In this study, besides the subjective evaluation of clenching or grinding teeth, the authors also used polysomnography as an objective and confirmatory criterion for bruxism diagnosis, reducing the prevalence from 12.5% (subjective only) to 5.5% (subjective+objective). Thus, it is plausible to expect that in the current study less than 7% did have a diagnosis of bruxism.