*Corresponding author e-mail: adisonlima@hotmail.com Introduction: The sleep-wake cycle of medical students is affected by their academic demands and class starting times. In spite the different sleep needs and characteristics, such as cronotype, they have to follow the same schedules. Therefore, it is necessary to know the relationship between cronotype and sleep quality. Methods: 234 students from 1st to 4th year of medicine's course of Federal University of Rio Grande do Norte were assessed. The Pittsburgh Sleep Quality Index was used to evaluate the subjective sleep quality. Scores of seven components were added to confer a global punctuation, which varies from 0 to 21. Punctuations below 5 indicate good sleep quality, 5-10 indicate poor sleep quality and above 10 indicate disturbance of sleep. The Epworth Sleepiness Scale was used to evaluate daytime sleepiness. The scale presents a maximum value of 24 points, and values above 10 indicate extreme daytime sleepiness. The Horne and Östberg (1976) questionnaire for “eveningness - morningness” dimension, was used to classify the participants in extreme morning (emt), morning (mt), intermediates (it), evening (et) and extreme evening types (eet). The punctuations are from 30 to 16 for eet and from 70 to 86 for emt. Results: The cronotype had a normal distribution, as in the total sample (12eet, 32met, 133it, 45mt and 03emt), regardless sex and period. The sleep quality showed value higher than 5 from 2nd to 4th years and less than 5 in the one of the first year; having as average 5,6 (SD= 1,1). The daytime sleepiness showed homogeneity among the periods, having average of 8,9 (SD=0,6). The cronotype and the sleep quality presented a linear relation (p<0,001) - et had a worst sleep quality than mt — with a specific significant relation between the components Cl (subjective sleep quality, p=0,02) and C3 (sleep duration, p<0,001). There was no significant relationship between cronotype and daytime sleepiness, although it was observed a predominance of excessive daytime sleepiness in emt. Conclusion: The most medical students show a low sleep quality, worst on the eet. The cronotype have influence on the sleep quality, probably due to the early class time in the 2nd to the 4th year and not so early in the 1st year, the et students have a better sleep quality in the 1st year decreasing along following years. In addition, it appears the evening types have some difficulty to adaptat to the college schedule. 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
Lima et al. (Thu,) studied this question.