The objective of this review was to investigate the impact of shift and night work on metabolic processes and the role of alterations in the sleep-wake cycle and feeding times and environmental changes in the occurrence of metabolic disorders. The literature review was performed by searching three electronic databases for relevant studies published in the last 10 years. The methodological quality of each study was assessed, and best-evidence synthesis was applied to draw conclusions. The literature has shown changes in concentrations of melatonin, cortisol, ghrelin, and leptin among shift workers. Melatonin has been implicated for its role in the synthesis and action of insulin. The action of this hormone also regulates the expression of transporter glucose type 4 or triggers phosphorylation of the insulin receptor. Therefore, a reduction in melatonin can be associated with an increase in insulin resistance and a propensity for the development of diabetes. Moreover, shift work can negatively affect sleep and contribute to sedentarism, unhealthy eating habits, and stress. Recent studies on metabolic processes have increasingly revealed their complexity. Physiological changes induced in workers who invert their activity-rest cycle to fulfill work hours include disruptions in metabolic processes.

OBJECTIVE:To estimate the prevalence of minor psychiatric disorders and to identify associated stressors among truck drivers. METHODS:A cross-sectional study was conducted with 460 truck drivers from a cargo transportation company of the Southern and Southeastern regions of Brazil, in 2007. Workers completed a questionnaire about sociodemographic, lifestyle and working conditions data. Working conditions were the independent variables, including occupational stressors, job satisfaction and job demand-control. The outcome evaluated was the occurrence of minor psychiatric disorders. Multiple and univariate logistic regression analyses were performed. RESULTS:The prevalence of minor psychiatric disorders was 6.1%. The most frequently reported stressors were traffi c congestion, tracking control and extended working hours. High job demand, low social support and extended daily working hours, as reported by drivers, were associated with minor psychiatric disorders. CONCLUSIONS:Work involving extended working hours was associated with the occurrence of minor psychiatric disorders, both in the analysis of general working conditions and as a factor considered to be a stressor by drivers. Thus, regulation of working hours with focus on the limitation of the daily working hours is necessary to reduce the chance of developing minor psychiatric disorders in drivers.

This study aimed to analyze individual cortisol levels in relation to work conditions, sleep, and health parameters among truck drivers working day shifts (n = 21) compared to those working irregular shifts (n = 21). A total of 42 male truck drivers (39.8 ± 6.2 yrs) completed questionnaires about sociodemographics, job content, work environment, health, and lifestyle. Rest-activity profiles were measured using actigraphy, and cardiovascular blood parameters were collected. Salivary cortisol samples were obtained (i) at waking time, (ii) 30 min after waking, and (iii) at bedtime, during both one workday and one off day from work. Irregular shift workers showed significantly higher waist-hip ratio, VLDL-cholesterol, tiredness after work, years working as a driver, truck vibration, and less job demand compared to day workers (p < .05). High cortisol levels in irregular shiftworkers were correlated with certain stressors, such as short sleep duration and low job satisfaction, and to metabolic parameters, such as total cholesterol, HDL, LDL, VLDL, and triglycerides. Day workers had higher cortisol levels collected 30 min after waking (p = .03) and a higher cortisol awakening response (CAR, p = .02) during workdays compared to off days . Irregular shiftworkers had higher cortisol levels on their off days compared to day shiftworkers (p = .03). In conclusion, for the day workers, a higher cortisol response was observed on workdays compared to off days. Although no direct comparisons could be made between groups for work days, on off days the irregular shiftworkers had higher cortisol levels compared to day workers, suggesting a prolonged stress response in the irregular group.In addition, cortisol levels were correlated to stressors and metabolic parameters. Future studies are warranted to investigate further stress responses in the context of irregular work hours. (Author's correspondence: crmoreno@usp.br)

RESUMO: Objetivos: A prevalência de problemas de sono em idosos, como insônia, é uma questão relevante em nossa sociedade. A má qualidade do sono, por exemplo, é vista por muitos como um resultado inevitável do envelhecimento. Neste contexto, este estudo teve como objetivo estimar a prevalência e os fatores associados a distúrbios do sono em homens e mulheres idosos (60 anos ou mais). Métodos: O presente trabalho é parte do estudo de coorte Saúde, Bem-Estar e Envelhecimento (SABE), realizado em São Paulo, Brasil. A amostra deste estudo transversal constituiu-se de 1.334 idosos com 60 anos ou mais. Os distúrbios foram avaliados com base nas respostas dos participantes, levando em conta se eles tinham experimentado qualquer perturbação do sono no mês anterior. Resultados: Dentre os avaliados, 44,9% indicaram distúrbios do sono em geral, sendo esses mais frequentes em mulheres (51,5%) e na faixa etária de 75 a 79 anos (48,2%). De acordo com a análise de regressão, gênero, doenças articulares, noctúria e incontinência urinária foram associados aos distúrbios, sobre os quais também foi verificado que seu aumento não é linearmente dependente da idade. Conclusões: Sexo, dor, incontinência urinária e noctúria são fatores associados a distúrbios do sono em idosos. Assim, concluímos que a sua ausência está associada ao gênero e ao estado de saúde.