Melatonin, leptin, insulin resistance and dietary intake during shift workers' rotation

Objective: to determine changes and correlations of salivary melatonin levels, food intake, serum concentrations of leptin, insulin and glucose and insulin resistance index (IRI) after seven night shifts. Higher risk of obesity and diabetes and modifications in melatonin concentrations have been registered in night shift workers. Materials and Methods: ten male security guards who work day shifts from 6 a.m. to 3 p.m. and night shifts from 10 p.m. to 6 a.m. were chosen to participate in this comparative -descriptive exploratory study. Anthropometric variables from the subjects were taken. Food intake data was taken the last daily shift and after the end of the last night shift. Also blood and saliva samples were taken at 7 a.m. and saliva samples were taken at 1 p.m. 9 p.m and 2 p.m in order to determine several biochemical parameters. Results: after seven nights of work, the levels of melatonin, glycemia and leptin at 1pm were greater. Total consumption of calories increased, at the expense of proteins and carbohydrates. The negative correlation between melatonin and insulin resistance was not statistically significant. Conclusions: the effects of the night shift over melatonin levels were confirmed the day after the work shift ended. Throughout the night shift, workers consumed more calories, and had higher levels of glycemia increasing the risk of developing obesity and diabetes. Leptin level increases were also observed, which may increment the risk of suffering metabolic syndrome.