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Effect of melatonin on the nocturnal sleep of overweight night workers


Shift and night work reverses the sleep-wake cycle of workers, leading to the suppression or reduction of melatonin production, which may be one of the causes of sleep problems among these individuals. In addition, some studies reported sleep problems associated with overweight.


To evaluate the effect of melatonin supplementation on sleep aspects of overweight night nursing professionals, according to chronotype


This was a randomized, double-blind, crossover clinical trial. The objective (via actigraphy) and subjective aspects of sleep (Visual Analog Scale - VAS) were evaluated. To assess the effect of the intervention and chronotype on sleep variables, a two-way repeated measures ANOVA (chronotype and intervention) (post-hoc LSD) was performed


Twenty-seven night workers completed the study protocol, with a mean age of 38.2 year-old (SD=5.9 years), the majority worked as a nurse (51.8%) and had been working at the night shift for a mean time of 9.2 years (SD=6.4 years). It was found that in the sleep performed between shifts, after the melatonin intervention and after the placebo, the participants woke up later than they did at the baseline (9:36 h; 9:31 h; 8:12 h, wake up time, respectively). Moreover, during the intervention they slept longer while using melatonin (539.4 minutes) compared to placebo (512.6 minutes). On the days off, sleep duration was longer while using melatonin (529.4 minutes) compared to placebo (496.6 minutes). Better scores were found for sleep quality and sufficient sleep to feel rested on working days while using melatonin (7.4 and 7.3 points, respectively) compared to placebo (6.9 and 6.5 points, respectively) and to the baseline (6.2 and 5.2 points, respectively). The late types had later sleep habits than the intermediate and early types.


Melatonin supplementation improved the perception of quality, duration, and perception of enough sleep to rest among overweight night nurses


Sleep; Melatonin; Night Shift Work


Área Básica


Pollyanna Pellegrino, Luciana Fidalgo Nogueira, Catia Peixinho Reis, Teresa Paiva, José Cipolla Neto, Claudia Roberta de Castro Moreno, Elaine Cristina Marqueze