Sleep Complaints Among Ex-Night Workers - Are There Residual Effects of Night Work on Sleep?

*Corresponding author e-mail: rotenber@ioc.fiocruz.br Introduction: Data on persistent effects of night work on sleep are scarce and controversial. The aim of this study is to in vestigate possible persistent effects of night work on sleep among femalenursing personnel. Methods: A cross-sectional study was carried out with female registered nurses and nurse assistants at three hospitals. A multidimensional questionnaire was used including information on work schedules throughout occupational life. Daytime workers (N=680) were classified into two groups: exclusive daytime workers, corresponding to those with no experience on night work (N=281) and former night workers (N=399). Former night workers were divided into two groups in accordance with the time spent on nocturnal work (from 3 to 9 years or 10 years or more). They were also classified in two groups according to self-reported sleep problems (difficulty falling asleep, difficulty maintaining sleep, early morning awakening, general complaint on insomnia (corresponding to reporting any of the above-mentioned problems), and unsatisfactory sleep. Binomial logistic regression was used to evaluate the association between the night work experience and referred sleep problems (exclusive daytime work as the reference group). Results: Significant associations were observed between the experience on night work and three out of the five studied sleep problems. Adjusted odds-ratio (and CI95%) for difficulty maintaining sleep, insomnia, and unsatisfactory sleep were 1.71 (1.05-2.79), 1.51 (1.01-2.25) and 1.59 (1.07-2.35), respectively, after controlling for potential confounders (age, schooling degree, income, presence of children, marital status, professional and domestic worked hours/week, professional category, type of contractual employment, hypertension, body mass index, alcohol consumption, and smoking habits). Compared to workers who never worked at night, workers who have spent 10 years or more on nocturnal work have 2.16 times a greater chance of having nocturnal sleep interrupted (OR=2.16), and have 1.87 times more chances of having a general complaint of insomnia. In relation to dissatisfaction with sleep, workers who spent between 3 and 9 years in nocturnal work had 1.62 times (OR=1.62; 1.02—2.58) greater chances of referring to dissatisfaction with sleep than those that never worked at night. Conclusions: Results suggest that there are residual consequences of night work on some of the studied sleep problems, particularly for those who have spent 10 years or more no nocturnal work. Those data can subsidize discussions on the adoption of legislative actions to limit exposure to night work. Support: Faperj; CNPq; Mount Sinai School of Medicine (Program on Occupational Health) 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