Does Melatonin Affect Fertility?

Why Fertility Researchers Care About a Sleep Supplement

Melatonin isn't just a sleep hormone. It's one of the most powerful antioxidants your body produces, and your ovaries contain some of the highest concentrations of melatonin receptors in the entire body. This isn't a coincidence — melatonin plays a direct role in protecting eggs from oxidative stress during their final stages of maturation.

Follicular fluid (the liquid surrounding your developing egg) contains melatonin at concentrations significantly higher than blood levels. Research has shown that women with higher follicular fluid melatonin levels tend to have better quality eggs during IVF retrievals.

The Evidence For Women

Egg Quality and IVF Outcomes

A 2012 study by Tamura and colleagues published in the Journal of Pineal Research gave 3mg of melatonin to women undergoing IVF who had previously had poor egg quality. The results were notable: the melatonin group had a significantly higher rate of mature eggs and better fertilization rates compared to controls. The researchers attributed this to melatonin's antioxidant protection of the developing oocyte.

A subsequent study from the same group found that women who took melatonin had higher concentrations of the antioxidant in their follicular fluid and lower levels of a marker of oxidative damage (8-OHdG) in their follicular fluid.

Ovarian Reserve and Anti-Müllerian Hormone

Some preliminary research suggests melatonin may support ovarian reserve. A small 2017 study found that women with diminished ovarian reserve who supplemented with melatonin showed improvements in AMH levels and antral follicle counts after 3-6 months. However, this was a small study and needs replication before drawing firm conclusions.

PCOS and Melatonin

Women with PCOS often have disrupted circadian rhythms and lower melatonin levels. A 2018 study in the Journal of Clinical Endocrinology & Metabolism found that melatonin supplementation improved insulin sensitivity and reduced androgen levels in women with PCOS — both of which can improve ovulatory function.

What About Men?

The research on melatonin and male fertility is more limited but generally positive. A 2014 study found that melatonin supplementation improved sperm motility and reduced DNA fragmentation in infertile men, likely through its antioxidant effects. Sperm, like eggs, are vulnerable to oxidative damage during production and maturation.

Practical Guidelines for TTC

• Dose: Stick to 0.5-3mg. Most fertility-related studies used 3mg. Start low and increase only if needed.
• Timing: Take it 30-60 minutes before bedtime. This aligns with your body's natural melatonin surge.
• Duration: Studies typically ran 3-6 months. This aligns with the timeline of egg maturation (about 90 days from recruitment to ovulation).
• Avoid high doses: Anything over 10mg moves into territory where ovulation suppression becomes a concern.
• Quality matters: Melatonin supplements are not well-regulated. A 2017 study in the Journal of Clinical Sleep Medicine found that actual melatonin content varied from -83% to +478% of what was listed on the label.

What We'd Buy

The Bottom Line

Melatonin is unusual in the fertility supplement world because the evidence is actually encouraging rather than ambiguous. At low doses (3mg or less), it appears to protect egg quality through antioxidant activity, may improve IVF outcomes, and could support ovarian function in women with PCOS. The critical caveat: high doses can suppress ovulation, so more is definitely not better.

If you're already taking melatonin for sleep and you're TTC, you can likely continue at a low dose. If you're considering starting it specifically for fertility, discuss it with your doctor — especially if you're also taking other supplements or medications that could interact.