Melatonin supplementation may help counteract DNA damage caused by night shift work, according to a small clinical trial published in Occupational & Environmental Medicine. The researchers suggest further studies should be conducted with different doses and long-term effects of melatonin supplements.
Night shift workers have suppressed nighttime production of the body’s clock hormone, melatonin. This reduces their ability to repair oxidative DNA damage, which is a byproduct of normal cellular processes and increases the risk of certain cancers in these individuals.
To investigate whether melatonin supplementation could help offset this damage by enhancing DNA repair capabilities, researchers studied 40 night shift workers. Half were randomly assigned daily doses of a 3 mg melatonin pill taken with food before going to sleep during the day for four consecutive weeks. The other half received identical-looking dummy pills.
All participants worked at least two consecutive nights every week, lasting seven hours or more, for six months prior to the study and did not suffer from any sleep disorders or long-term conditions. Urine samples were collected before starting the trial and near its end during daytime naps and subsequent night shifts while they wore activity trackers.
The researchers measured levels of 8-OHdG in all urine passed during periods of daytime sleep and following night shift work, an indicator of DNA damage repair capacity. They found that urinary 8-OH-dG was significantly higher (by 80%) among those taking the melatonin supplement compared to those taking the dummy pill.
However, there were no significant differences in urinary 8-OHdG levels during subsequent night shifts. The study’s limitations include its small size and that most participants worked in healthcare settings. Natural light exposure was not accounted for either, which affects circulating melatonin levels.
The researchers note increased oxidative DNA damage due to diminished repair capacity is a strong mechanism behind the carcinogenic effects of night shift work. Their trial suggested that melatonin supplementation could improve this damage repair capability among night shift workers.
They call for larger-scale studies examining varying doses and long-term impacts of melatonin supplements to validate these findings. They conclude, “Pending such research outcomes, melatonin supplementation may be a viable intervention strategy to reduce cancer risk among night shift workers.”
The team emphasizes the importance of assessing long-term efficacy since prolonged use over years would be necessary for maximum prevention benefits.
