*Corresponding author e-mail: ivanise@cb.ufrn.br Introduction: The Adolescence is characterized for later sleep schedules influenced by biological and social factors. With the passage of school grades, the adolescents are under an increase of the load of school and social pressure that would contribute to the sleep delay. This factor together with the school time in the morning are related to sleep partial deprivation with negative consequences to the adolescent health. Objective: To compare the sleep habits of Brazilian adolescents from 11th to 12th grade. Methods: Students from two private schools in Natal/RN participated with 158 adolescents from 11th grade (age between 14 and 17 years) and 213 students from 12th grade (aged 15 and 18 years). The “Health and Sleep” questionnaire was applied to characterize the sleep habits and pattern. The sleep habits were compared using the chi-square and the sleepwake schedules by using the t -test for independent samples. For both, the level of significance considered was 5%. Results: From Monday until Thursday and on Sunday the bedtime was seen to be later for the 12th grade students compared to that for 11th grade students. The reasons for the late bedtime reported by most students were TV and computer using, but on weekends the 12th grade students reported “to study” and “to go to the parties” with higher frequency. The wake-up schedules showed no difference between the two groups. On weekdays, the reasons to wake-up time reported by most students were the “school schedule” and on the weekends, “not being sleepy”. In addition, on weekends the 12th grade students report to wake-up to study with a higher frequency. The students from both grades took naps in common times, but the 12th grade students wake up earlier and spent less time sleeping. Moreover, this group reported greater participation in extra-school courses and lesser practice of exercise. Conclusion: At the 12th grade the students sleep later and the report of bedtime and wake up time due to study increases on weekends. Besides, the length of the nap decreases due to increased participation in extra-school courses. The decrease in physical activity can be considered as a negative effect of high school load. Publication History Article published online: 16 June 2026 © 2009. Brazilian Sleep Academy. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil
Sousa et al. (Thu,) studied this question.