Effects of Exogenous Melatonin Administration on Psychic Symptoms in Fixed-Shift Workers During Climacteric

Introduction: Menopause is the point at which menstruation permanently ceases, defined by the absence of menstrual periods for 12 consecutive months, typically occurring between the ages of 45 and 55. The climacteric, the period in which menopause takes place, is characterized by hormonal changes, a decline in follicular activity and fertility, as well as alterations in the menstrual cycle. In addition to physical symptoms such as hot flashes and night sweats, this phase is often associated with increased levels of stress, anxiety, and depression, which impact mental health and quality of life. These effects may be exacerbated in shift workers, especially night workers, due to circadian rhythm dysregulation and a possible reduction in endogenous melatonin levels. The objective of this study was to analyze the effects of exogenous melatonin administration on stress, anxiety, and depression symptoms in 46 female workers across different work shifts during the climacteric period.

Methods: This study, a randomized clinical trial, was conducted with 46 nurses working in three shifts: morning (7h-13h, n = 16), afternoon (13h-19h, n = 15), and night (19h-7h, n = 15) in a hospital in São Paulo. In each shift, participants were divided into an intervention group and a placebo group. The intervention group received 0.3 mg of melatonin to be administered on alternating nights. The placebo group received an identical capsule and the same instructions. Data collection was performed using the Depression, Anxiety, and Stress Scale (DASS-21).

Results: The participants had a mean age of 47.2 years, and 34.7% had already gone through menopause. The intervention group in the night shift showed a significant reduction in stress after the intervention (Wilcoxon test, p = 0.04), with scores decreasing from the moderate to the normal range, while the placebo group maintained higher levels. No differences were observed in baseline depression scores after the intervention among morning shift workers. However, after three months of study, the Mann-Whitney test showed that the intervention group had a significant difference in depression scores compared with the placebo group (p = 0.03) in this shift, with scores improving from the moderate to the normal range. On the other hand, no significant differences were found in anxiety scores in any of the analyzed shifts.

Conclusion: The administration of exogenous melatonin significantly reduced stress scores in night shift workers during the climacteric period. Additionally, in the morning shift, after the intervention, depression was significantly lower in the intervention group compared with the placebo group. No effects of the intervention on anxiety were observed in any shift or group. Support: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001 and Fapesp (2019/24327–5; 2022/04365–2).

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Artikel online veröffentlicht:
08. Oktober 2025