A small clinical trial published in Occupational &amp; Environmental Medicine&nbsp;suggests that melatonin supplements may help counteract DNA damage linked to night shift work by enhancing the body&rsquo;s repair mechanisms.
While this could, potentially, decrease the risk of cancer among this population, the researchers&mdash;including those from the British Columbia Cancer Research Institute in Canada&mdash;conclude that larger studies exploring different dosages and the long-term effects of melatonin supplementation are necessary.
Night shift workers experience suppressed production of melatonin, a hormone regulated by the body&rsquo;s internal clock. This suppression impairs the body&rsquo;s ability to repair oxidative DNA damage, a natural by-product of cellular processes, potentially increasing cancer risk. The study aimed to determine whether melatonin supplementation&mdash;considered a &lsquo;physiological support&rsquo; to help the brain restore the quality, structure, and pattern of sleep&mdash;could enhance DNA repair in 40 night shift workers.
Participants were randomly assigned to receive either a daily 3 mg melatonin supplement or a placebo, taken with food an hour before their daytime sleep for four weeks. All participants had been working at least two consecutive night shifts per week, lasting at least seven hours per night, for at least six months. None had sleep disorders or chronic health conditions.
Urine samples were collected during two consecutive daytime sleep and night shift periods&mdash;once before starting the trial and again at the end of the four-week period. Activity trackers recorded daytime sleep duration. The study measured levels of 8-OHdG, a biomarker for DNA damage repair capacity, in all urine collected during daytime sleep and subsequent night shifts.
Results showed that urinary levels of 8-OHdG were 80% higher during daytime sleep among those taking melatonin, suggesting improved DNA repair compared to the placebo group. However, no significant difference was observed during night shifts.
The researchers acknowledge that the study&rsquo;s small sample size and its focus on healthcare workers may limit its applicability to other professions. Additionally, they could not account for variations in natural light exposure, which affects melatonin levels.
Despite these limitations, they highlight the potential role of diminished DNA repair in the cancer risk associated with night shift work. The findings indicate that melatonin supplementation might enhance oxidative DNA repair capacity in night shift workers.
The researchers call for larger-scale studies to assess different melatonin dosages and long-term effects. They emphasize that if future studies confirm these benefits, melatonin supplementation could become a viable strategy to reduce cancer risk among night shift workers. Given the long-term nature of night shift work, understanding the sustained efficacy of melatonin supplementation is crucial for maximizing potential health benefits.

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Night shift work lowers melatonin, hindering DNA repair and raising the risk of oxidative damage

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February 25, 2025 | 16:04 IST