Melatonin is a hormone that regulates our sleep-wake cycle, otherwise known as our circadian rhythm. In addition to this most infamous role, new research shows it also may play a role in fertility¹.

But how does melatonin work, and how may it affect your fertility? Learn more about melatonin and fertility, how to increase your levels and melatonin’s safety profile.

What is Melatonin?

Melatonin is a hormone produced by the pineal gland in your brain that plays a role in sleep. The amount of melatonin released varies depending on the time of day. In general, it increases at night to support sleep and decreases with natural light to help you wake more easily in the morning. 

Our bodies naturally produce melatonin, but this ability declines with age. Low melatonin levels are associated with sleep issues such as insomnia and jet lag. Additionally, if you are exposed to light at night, this can block melatonin production².

Melatonin also plays a role in other areas such as mood and depression, stress, immune function, and fertility. It may do this by functioning as an antioxidant to fight free radicals; harmful toxins that can damage our health³.

It is through its function in limiting oxidation in the body and helping preserve egg quality that it may be beneficial for fertility⁴.

Melatonin and Fertility

Melatonin is found in high levels in the ovaries and follicular fluid. Because of this, studies have been underway to determine if there is an association between melatonin and fertility⁵.

There are many known causes of infertility, but many times there is no clear answer. Some say that unexplained infertility may be due to oxidative stress in the ovaries and human egg cells. Melatonin is an antioxidant thought to play a role in improving egg quality and pregnancy outcomes through its ability to reduce oxidative stress.

Here are a few studies that have shown a relationship between melatonin and fertility:

Study 1:  Sixty-one women were recruited who were undergoing IVF cycles. Higher melatonin levels in the follicles were correlated with improved ovarian reserves and IVF outcomes⁶. 

Study 2: A systematic review was conducted that evaluated 5 studies. Those undergoing assistive reproductive technology (ART) were given 3 milligrams (mg) of melatonin per day for two weeks. Those with higher melatonin levels had more high-quality embryos and more successful implantation⁷.

Some of the studies reviewed however used other supplements such as myoinositol and folic acid in addition to melatonin, making it difficult to determine if the outcomes were specifically due to the melatonin alone.

Study 3: A review study included an evaluation of 10 different studies. Overall, melatonin treatment was seen to increase clinical pregnancy rates but not live birth rates in ART cycles.⁸

Based on the research to date, it appears melatonin does play a role in increasing clinical pregnancy rates in certain cases. More research and larger studies are needed on how melatonin alone can affect miscarriage, live birth rates, and pregnancy outcomes without the addition of any other potential fertility-enhancing supplements.

Supporting Healthy Melatonin Levels

Melatonin is naturally produced by our bodies, but the body may not always produce enough. Here are a few things you can do to make sure yours is producing as much as possible:

Eat melatonin-rich foods

Certain foods are good sources of melatonin such as tart cherries or cherry juice, goji berries, eggs, milk, fish, and nuts. Eating these foods regularly can support healthy melatonin levels and optimize your nutrition at the same time ⁹.

Dim the lights at night

Keeping things dark at night signals your body to release melatonin. When this happens, it helps regulate your body’s internal clock, keeping your body (and your stress levels!) in better balance. 

This also means limiting exposure to blue light from phones and devices at least 2 hours before bedtime. If this is not realistic for you, consider wearing blue light-blocking glasses, dimming the brightness of your electronic screen, or putting your phone on night mode¹⁰. 

There are also apps available that you can turn on at night to reduce blue light emissions.

Create a consistent bedtime schedule

Getting to bed and waking up around the same time every day helps regulate your melatonin levels. Your body begins to know what to expect, and in this way can release melatonin more easily when it is needed.

Get in sunlight

When exposed to sunlight your body produces serotonin, a precursor to melatonin. Serotonin has been seen to convert to melatonin after dark, helping your body to naturally produce more of it¹¹.

While these are some of the natural ways to support melatonin levels, you may be curious about the pros and cons of melatonin supplementation.

Melatonin Supplements

It’s important to keep in mind that supplements are more likely to benefit you if your body is deficient in what you’re supplementing it with. In other words, if your body is naturally producing enough melatonin, there may not be any benefit from taking any additional. 

Your melatonin levels can be checked via a blood, urine, or saliva test. Out of all three tests, the blood, otherwise known as the plasma test, is said to be the most accurate at detecting low melatonin levels. 

If a blood test is too invasive or not possible for you, the saliva test is almost as accurate.

The blood and saliva tests are more accurate as they are able to show true melatonin concentrations at the exact timing of the test, whereas a urine test displays an accumulated level over a period of time¹².

There is no universal standard for ideal melatonin levels, as they can vary significantly based on age, sex, medical condition, and the time of day of your test. 

According to research, an ideal melatonin level can vary anywhere from 10-85 ng/mg. Melatonin levels tend to be lower (10-20 ng/mg) if you’re checking them during the day, and higher at night according to the body’s natural circadian rhythm¹³.

It’s recommended to speak to your doctor about your individual results and the ideal level for you.¹⁴ 

If you take melatonin supplements, most manufacturers recommend taking them 1-2 hours before bedtime when it’s already dark. If you take it during the day or at the wrong time, it can throw off your sleep-wake cycle.

The most common melatonin dose studied regarding fertility is 3 milligrams (mg) per day. Keep in mind that everyone’s tolerance is different. Always consult with your doctor on what is best for you, especially as melatonin at high doses can potentially interfere with ovulation¹⁵.

Melatonin Safety

Melatonin is generally considered safe, but there are a few potential side effects and interactions to pay attention to¹⁶.

Side Effects

• Headaches
• Nausea
• Abdominal cramps
• Depression/mood changes
• Anxiety
• Reduced alertness
• Disorientation

It is not advised to be taken while pregnant or breastfeeding. Additionally, it can interact with certain medications and supplements ¹⁷.

Interactions

• Contraceptives
• Blood thinners
• Herbs/supplements
• Blood pressure medications
• Diabetes medications
• Immunosuppressants
• Anti-seizure medications
• Antipsychotics

You may have heard the possibility of becoming dependent on melatonin or that taking it decreases your body’s natural production of melatonin. Research has not shown this to be true as of yet, but most studies have been in the short term¹⁸.

More long-term research is needed to determine if these dependence risks are possible. Until then, if you are to take melatonin it’s best to not take it for longer than a few months.

It’s always best to speak to your doctor before starting melatonin to discuss the pros and cons and determine the best dose for you.

Conclusion

If you’re struggling with infertility, you are probably trying to do everything possible to increase your chances of conception. While some studies on melatonin and fertility are promising, it is not advised to take melatonin routinely to improve fertility. 

More research is needed to determine melatonin’s effect on live birth rates (LBR), miscarriage, and pregnancy outcomes.

To optimize fertility and pregnancy outcomes, it’s best to target it through a holistic lens. It is often a combination of a healthy fertility diet, exercise regimen, lifestyle, and supplements that is most beneficial versus one single intervention or supplement.  

Always consult with a trusted medical team for support and guidance in your fertility journey.

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