The aim of this study was to verify sleep hours and associated factors among Brazilian and Spanish students. A cross-sectional study with students aged 11 to 16 years-old was carried out in Paranavaí, Brasil (n = 264) and Cáceres, Spain (n = 233) between 2013 and 2015. Sleeping hours were verified regarding time in minutes, sleep in weekdays, weekends and after lunch/Siesta. All data were checked for normality by the Kolmogorov-Smirnov test. Mann-Whitney U test, Chi-square test (X2) and Odds Ratio estimates were used (p < 0.05). High prevalence in both groups of sleeping 8 hours or more a night at the weekend. The prevalence of sleeping on weekdays, > 8 hours, 6 to 8 hours and < 6 hours among Spanish and Brazilian students, respectively. Nearly a quarter of each group responded that makes the siesta. Spanish students had 3 times higher chance to sleep < 8 hours a night in weekdays, among students from 14 to 16 years old and among the underactive. At the weekends the chance of sleeping < 8 hours is 2 times greater among the Spanish students. Simple guidelines could help so that sleep habits do not affect school development, such as practicing physical activity regularly, sleeping at least 8 hours a night, avoid excessive access to technology at night.