Bedtime Administration of Melatonin to Healthy Females Does Not Alter Menstrual Characteristics

Rapid travel across multiple time zones often results in fatigue, sleepiness, insomnia, and poor mental performance. These symptoms, in addition to others, often are known as jet lag or desynchronosis. Melatonin, an endogenously occurring hormone, has been shown to be capable of resynchronizing circadian rhythm disruptions and inducing sleep in humans, and therefore can be effective in preventing sleep loss and maintaining alertness during travel. However, in females, melatonin has a potential inhibitory influence on the hypothalamo-pituitary-ovarian axis, and its use may result in secondary disruptions of the menstrual cycle. The study reported here was double blind and placebo controlled and was undertaken to determine whether exogenous melatonin (10 mg), given at bedtime for 7 consecutive days, would have an effect on menstrual characteristics. Our results show that during the late follicular and early luteal phase of the monthly cycle, exogenous melatonin has no apparent effect on menstrual characteristics. There were no systematic monthly surge in luteinizing hormone. Under the specific conditions reported here, any effect of exogenous melatonin on menstrual characteristics should not be a concern.