Melatonin is a naturally occurring hormone primarily produced by the pineal gland in the brain. Its well-known role involves regulating the body’s sleep-wake cycles, often referred to as circadian rhythms. The body’s production of melatonin increases in darkness, signaling the brain and other organs about changing light conditions, which helps dictate when a person feels sleepy and wakes up.
Melatonin’s Influence on Reproductive Function
Melatonin influences reproductive function in both females and males. In females, it plays a role in ovarian function, affecting egg quality and hormone regulation essential for ovulation. Melatonin receptors are found in female reproductive cells, indicating direct action.
High concentrations of melatonin in follicular fluid act as a powerful antioxidant, protecting developing eggs from oxidative stress that can harm egg quality and embryo development. It can reduce reactive oxygen species and improve mitochondrial function, aiding oocyte maturation, fertilization, and embryo development. Melatonin also helps regulate hormones like GnRH, LH, and FSH, which are crucial for the menstrual cycle and ovulation.
In males, melatonin’s impact on fertility is also significant, particularly concerning sperm quality, motility, and testicular function. Its antioxidant properties may protect sperm from oxidative stress and DNA fragmentation. Some research suggests melatonin supplementation can enhance sperm count, improve motility (sperm’s ability to swim), and optimize morphology (sperm size and shape).
Melatonin influences testicular function by modulating Leydig cells, which produce testosterone, and Sertoli cells, which support sperm development. It can help reduce cell death and oxidative stress in the testes, contributing to improved sperm quality. While some studies in healthy men show a decrease in sperm concentration and motility with long-term use, other research highlights its beneficial antioxidant and anti-inflammatory effects on testicular health.
Supporting Fertility with Melatonin
Melatonin supplementation is being investigated for its potential to support fertility, especially with assisted reproductive technologies like in vitro fertilization (IVF). Studies show oral melatonin can increase levels in follicular fluid, improving oocyte quality and fertilization rates. For example, a study of women with poor oocyte quality in IVF found 3 mg/day of melatonin significantly increased fertilization rates in later cycles.
Melatonin’s antioxidant properties are a key reason for its potential benefits in fertility treatments, as oxidative stress can harm oocytes and embryos. Supplementation has been linked to improvements in mature oocytes, higher quality embryos, reduced embryo fragmentation, and increased implantation rates. For women with unexplained infertility, melatonin (3 mg/day or 6 mg/day) has improved intrafollicular oxidative balance and oocyte quality, leading to a slight increase in pregnancy and live birth rates.
Melatonin also shows promise for women with polycystic ovary syndrome (PCOS), a common fertility condition often linked to poor oocyte quality. Research indicates melatonin supplementation can improve IVF outcomes for women with PCOS, increasing mature oocytes, high-quality embryos, and clinical pregnancy rates. One study found 2 mg of melatonin for six months in PCOS patients significantly improved sex hormone levels, including decreased androgens and increased FSH, with 95% experiencing menstrual cycle improvements.
Important Safety Considerations
While melatonin is natural, it is not a benign supplement and requires careful consideration, especially when trying to conceive. Common side effects include headache, sleepiness, dizziness, and nausea. Due to its sedating effects, avoid driving or operating machinery for 4-5 hours after taking it.
Melatonin can interact with various medications, potentially increasing their sedative effects or impacting their efficacy. These include:
Antidepressants (e.g., fluvoxamine, amitriptyline)
Benzodiazepines (e.g., temazepam, diazepam)
Blood pressure-lowering medications
Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen
Estrogens (in contraceptives or hormone replacement therapy)
Melatonin might also slow blood clotting, increasing the risk of bruising and bleeding when taken with anticoagulant drugs like warfarin.
For individuals trying to conceive, it is important to consult a healthcare professional before starting melatonin supplementation. High doses, especially combined with progesterone, have inhibited ovulation in some cases. While 3 mg per day is a common dosage studied for fertility, the optimal dose and duration for fertility support are still being researched, and individual needs vary.