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Exogenous melatonin supplementation decreases insomnia symptoms in overweight night works


Insomnia is a relevant public health problem, both because of its high prevalence and associated comorbidities. An important risk factor for insomnia is night work, a very common work scheme to nursing professionals.


To evaluate the effect of exogenous melatonin supplementation on insomnia symptoms in overweight nursing professionals who worked fixed night shifts (12x36 hours).


A controlled, randomized, double-blind, crossover clinical trial was conducted with 27 nursing professionals. Exogenous melatonin (3 mg) was administered for three months, as well as placebo, in off-work nights, in a randomized manner. Insomnia symptoms were evaluated using the Karolinska questionnaire, and those who presented at least one of the seven symptoms three times a week or more were categorized as insomnia. The effect of melatonin on the prevalence of insomnia symptoms was evaluated, with p < 0.05 being considered significant, as was the mean number of insomnia symptoms before and after operations.


The mean age of the participants was 37 (SE 11 years-old), and with the majority being married (59.3%). More than half of the interviewees were nurses (55.6%) and 44.4% were nursing technicians, with a mean of 5.6 years of work in the function. As reasons for working at night, 40.7% reported the need to reconcile their profession with caring for the home, and 92.6% did not have a second job. Moreover, 70.4% reported having worked the night shift before the present job. Of the seven insomnia symptoms assessed, it was found at baseline that the most prevalent was feeling tired upon waking (63%), followed by feeling exhausted upon waking (55.5%) and early awakening (33.3%). The prevalence of insomnia symptoms at baseline was 77.8%. After exogenous melatonin supplementation, the prevalence significantly decreased to 22.2%, rising to 74.1% after placebo use. The result of repeated measures ANOVA (post-hoc Bonferroni) showed a significant decrease in the mean number of insomnia symptoms after melatonin supplementation (0.3 symptoms, SE 0.13), both compared to baseline (2.3 symptoms, SE 0.33), as after placebo use (2.0 symptoms, SE 0.4).


Melatonin supplementation decreased the prevalence of insomnia symptoms among overweight night works. Considering the high prevalence of insomnia symptoms as well as the characteristics of this population, exogenous melatonin may be useful in the treatment of insomnia symptoms among night fixed workers.


Insomnia symptoms, melatonin, night work, nursing.


Área Clínica


Universidade Católica de Santos - São Paulo - Brasil


Thaynara de Pontes Silva, José Cipolla Neto, Claudia Roberta de Castro Moreno, Elaine Cristina Marqueze