-This report presents an analysis of the complaints of increasing daytime sleepiness as well as a study on their possible effects on the academic performance of medical students at the University of Brasilia. The Epworth Sleepiness Scale was applied to 172 medical students, at the beginning of August 1997 and at the end of November 1997. Academic performance was measured by analyzing the number of SS grades (from 9.0 to 10 over ten) and MM grades (from 5.0 to 6.9) attained in exams at the end of that school period. The results showed that at the beginning of the semester, 68 (39.53%) of these 172 students already presented with excessive daytime sleepiness, and that of the 104 remaining students, 38 (22%) developed daytime sleepiness by the end of the semester. Furthermore, it was observed that the sleepier students did not achieve as well as the others on their final examinations. KEY WORDS: Epworth Sleepiness Scale, daytime sleepiness, medical students, academic performance.Sonolência diurna e desempenho acadêmico em estudantes de medicina Sonolência diurna e desempenho acadêmico em estudantes de medicina Sonolência diurna e desempenho acadêmico em estudantes de medicina Sonolência diurna e desempenho acadêmico em estudantes de medicina Sonolência diurna e desempenho acadêmico em estudantes de medicina RESUMO -Este trabalho analisa a relação entre queixas de sonolência diurna crescente e desempenho acadêmico de estudantes de medicina da Universidade de Brasília. A escala de sonolência de Epworth foi aplicada em 172 estudantes de medicina no início de agosto de 1997 e no final de novembro (respectivamente início e final do semestre letivo). Estudou-se o desempenho acadêmico pela análise do número de menções SS (valores entre 9,0 e 10,0) e MM (valores entre 5,0 a 6,9) obtidas no final do referido semestre letivo. Os resultados revelam sonolência diurna desde o início do semestre em 68 alunos (39,53%) e, nos 104 restantes, observou-se sonolência diurna crescente no decorrer do semestre em 38 alunos (22 %). Observou-se também que os estudantes mais sonolentos apresentaram pior desempenho acadêmico. PALAVRAS-CHAVE: Escala de Sonolência de Epworth, sonolência diurna excessiva, estudantes de medicina, desempenho acadêmico. The importance given to excessive daytime somnolence as a public health problem has increased lately, as it is one that affects almost 12% of all Americans 1 . Moreover, it has been held responsible for motor vehicle and work accidents, for difficulties in adapting to new situations, and for social maladjustment problems, as well as for a decrease in quality of life 2-5 . The literature describes an excessive occurrence of daytime somnolence in occupations such as professional drivers 6 , workers who do night shifts 7 , and medical residents 8 whose activities entail a lack of sleep as well as too much work, both of which cause stress.Despite the importance of these facts, little is to be found in the literature regarding daytime excessive drowsiness in medical students, not to mention the...