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The Role of Melatonin and the Circadian Rhythm in Female Reproduction

The Role of Melatonin and the Circadian Rhythm in Female Reproduction

Circadian RhythmMany of us know melatonin as a tiny little pill that we take to help us fall asleep, or help us recover from jet lag. What is less known about this hormone is that it actually plays a role in female fertility.

Melatonin is a hormone naturally produced by mammals, some plants, and even fungi. Melatonin helps regulate many other hormones in the body and helps to maintain our circadian rhythms. Circadian rhythms are the physical, mental and behavioral changes that follow an internal 24-hour cycle. Think of it as a “clock” of sorts; circadian rhythms play an important role in when we wake each day and likewise when we fall asleep – referred to as our sleep-wake cycles. During light hours of the day, our natural melatonin production in the body drops and, when it is dark, the body produces more melatonin. Too little light during the day, or being exposed to light, especially bright artificial light in the evening, can disrupt the body’s normal melatonin cycles.

The Importance of Melatonin for Female Fertility

Melatonin is produced by the pineal gland, a small endocrine gland located between the two hemispheres of the brain. In relation to fertility, melatonin is also produced by the follicles (eggs) within an ovary, the mass of cells that surround the follicles, and in the immature follicle itself.

Melatonin has been found to be a powerful free radical scavenger exerting strong antioxidant effects, important for supporting cellular health and protecting an immature egg from oxidative stress, especially at the time of ovulation. One small study of 115 women at the Yamaguchi University Graduate School of Medicine in Japan showed melatonin may increase egg quality by reducing the level of one oxidizing agent called 8-OHdG in the ovum, which is a natural product of DNA oxidation.

Another study in the Journal of Ovarian Research states that, “It has been believed that melatonin regulates ovarian function by the regulation of gonadotropin release in the hypothalamus-pituitary gland axis via its specific receptors… Higher concentrations of melatonin have been found in human preovulatory follicular fluid compared to serum, and there is growing evidence of the direct effects of melatonin on ovarian function especially oocyte maturation and embryo development.”

Melatonin also helps control body temperature, the timing and release of female reproductive hormones, and possibly egg quality. In fact, melatonin has been found to control the onset of puberty in females, the frequency and duration of menstrual cycles, and even when a woman stops menstruating and enters menopause.

Preliminary evidence suggests that melatonin may help strengthen the immune system as well.

During pregnancy, melatonin in the blood passes through the placenta not only supporting its function and health, but also aiding in the creation of the fetal suprachiasmatic nucleus or SCN, where a human’s central circadian regulatory system in located. Because of its antioxidant effects, Melatonin may also protect the developing fetus from oxidative stress.

In conclusion, recent research of the role of a healthy circadian rhythm and cyclical production of melatonin is proving to be critical for optimal female reproductive hormone function, menstrual cycle timing, and ovarian function (including follicle function- both health and quality), as well as placental function.

One can influence her circadian rhythms and melatonin production simply by waking when it becomes light outside and sleeping when it is dark. While we understand that many of us are not able to sleep the entire time it is dark outside, you can create a routine that allows you to slow and enjoy calm as darkness sets in and avoid bright artificial lights (from televisions, computer screens, hand-held devices, cell phones, etc.) at least one hour before bedtime at night (No TV in bed!).

What About Supplementing Melatonin?

If you are thinking about taking melatonin to boost your fertility, you should discuss the issue with your healthcare provider or fertility specialist.

Contraindications and Side Effects
There is potential for side effects when using melatonin and possibly interactions between melatonin and medications. Speak with your healthcare provider or a pharmacist about possible side effects or drug interactions, which can also be learned here:


Dr. Christine Traxler M.D., OB/GYN
Dr. Christine Traxler M.D., OB/GYN

Dr. Traxler is a University-trained obstetrician/gynecologist, working with patients in Minnesota for over 20 years. She is a professional medical writer; having authored multiple books on pregnancy and childbirth; textbooks and coursework for medical students and other healthcare providers; and has written over 1000 articles on medical, health, and wellness topics.  Dr. Traxler attended the University of Minnesota College of Biological Sciences and University of Minnesota Medical School,  earning a degree in biochemistry with summa cum laude honors in 1981,  and receiving her Medical Doctorate degree (MD) in 1986.

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  1. Avatar

    Doesn’t supplemental melatonin stop women from ovulating? For that reason I have been avoiding it.
    Thank you

    • Dear Norma,

      It has been found that for some women, taking melatonin may suppress ovulation, particularly if taking it in higher doses of 5 mg or more. I have not seen hard and fast evidence of this, but this is in part why I suggest that it is important to discuss taking a melatonin supplement with your healthcare provider if you are trying to conceive.

      Best wishes!

    • Avatar

      I am glad to see that melatonin possibly stops ovulation only at higher doses. I have been taking 3 mg so I am OK.

  2. Avatar

    Which melatonin do you recommend? Any specific brand or place to order? And how many mg?

    • Elizabeth Willett, MA, CH

      Hello Ellen!
      There are many brands of melatonin available in health food stores and pharmacies, but if you are thinking about taking melatonin to boost your fertility you should discuss it with your healthcare provider or fertility specialist. He/she will be able to guide you in the proper dose for your needs.

      Best wishes!

  3. Avatar

    It’s so sad that today we seem to have lost the ability to connect with our inner cycles!