How Melatonin Affects Your Hormones and Metabolism

Melatonin supplements are a common sleep aid, but how does melatonin affect hormones and metabolism? Let’s take a look at what melatonin can mean for your hormones and metabolism. After reviewing the science, you’ll be better equipped to determine whether you want to use melatonin or a melatonin free sleep aid.

Melatonin is a hormone your brain’s pineal gland naturally produces. It plays a crucial role in regulating your sleep-wake cycle, signaling your body that it's time to sleep and promoting drowsiness. 

Although people commonly associate melatonin with sleep, it’s one of nature’s most versatile biological signals and plays a role in many other bodily functions. In addition to regulating sleep, melatonin also helps modulate nighttime physiological processes, such as lowering your core body temperature, reducing your blood pressure, and influencing your mood by acting on neurotransmitters like serotonin and dopamine.

Melatonin levels peak in childhood and early adolescence, then decline steadily with age, particularly after age 40. This natural reduction may contribute to sleep disturbances in older adults and has even been implicated in the aging process itself, according to studies involving pineal gland function.

Melatonin doesn’t just regulate sleep, it influences your broader endocrine system by modulating how and when your pituitary gland releases other hormones. These effects ripple through your reproductive and metabolic processes, sometimes suppressing normal hormone activity, especially in healthy, premenopausal women.

For example, did you know you have higher levels of circulating melatonin in the winter? When the days are shorter and you typically have greater exposure to darkness, your melatonin levels rise. This coincides with people being metabolically slower during this time of year.

Melatonin is even active in your retinas, increasing night-time light sensitivity and helping your eyes adapt to natural day-night cycles.

Interestingly, many species that don’t mate in the winter have very high circulating melatonin levels that suppress their sex hormones. There are some preliminary human, primate, and other animal studies that point to melatonin’s suppressing effects on sex hormones. This is an important consideration for melatonin users also seeking to optimize their physical fitness or athletic performance.

Hormonal disruption occurs when an external factor, such as the introduction of a chemical, interferes or even blocks the normal functions of your body’s endocrine system. Examples of hormone disruptors, also called endocrine disruptors, include pesticides, certain preservatives (such as parabens), and many compounds in plastics and resins (like Bisphenol A, or BPA).

By making it impossible for your endocrine system to function as it should, hormonal disruption can cause a number of health issues. Researchers have found links between endocrine disruptors and problems related to reproduction, child development, neurology, and other areas.

Popular melatonin sleep supplements include Beam Dream, Zarbee’s, Olly, and others. However, prolonged or excessive use of melatonin supplements can disrupt the delicate balance of your hormones, leading to potential side effects and imbalances. For these reasons, you may decide to look for Beam Dream alternatives that don’t contain melatonin.

For example, melatonin can interact with cortisol (the stress hormone) and with the reproductive hormones estrogen and testosterone. It also interacts with the corticotropin-releasing hormone (CRH) system, which is involved in how your body uses energy and other processes. 

Melatonin may also act as an inhibitor of human chorionic gonadotropin (hCG), a hormone critical during pregnancy that signals to other areas of the body to initiate and sustain pregnancy. This interference could affect the production of androgens such as testosterone and DHEA, which play roles in reproductive health and physical development and fitness in both men and women.

These hormone interactions understandably raise some red flags about the long-term use of melatonin for people who are trying to maintain their fertility, lean body mass and protect their children.

MoonBrew is a popular melatonin-free sleep aid. However, its focus is more on relaxation and the onset of sleep versus muscle repair and recovery. Hence, users may want to look into a MoonBrew alternative like Thirdzy, which is also melatonin-free and focuses on both deep sleep and total recovery. 

Melatonin has potentially anti-estrogen effects, meaning it might reduce estrogen production or block its activity in the body. Some studies have shown that as melatonin levels increase, estrogen levels decline, and vice versa. In the long term, melatonin interfering with estrogen can disrupt a woman’s menstrual cycle or contribute to fertility complications.

In rare cases or with chronic overuse, excessive melatonin levels (a condition known as hypermelatoninemia) have been linked to serious endocrine and metabolic disorders, including polycystic ovary syndrome (PCOS), anorexia nervosa, and hypogonadotropic hypogonadism. Some case studies have even associated it with rare syndromes involving spontaneous hypothermia and excessive sweating (hyperhidrosis).

These hormone interactions understandably raise some red flags about the long-term use of melatonin for people who are trying to maintain their fertility, lean body mass, and physical fitness.

Don’t confuse melatonin’s potential to disrupt your hormones with the term “melatonin hormone disruptor,” as these refer to different things. While excessive melatonin use can interfere with your body’s hormones, a melatonin hormone disruptor refers to something that disrupts your body’s melatonin production. 

In other words, a melatonin hormone disruptor is any factor, chemical or otherwise, that can interfere with your body’s normal melatonin levels. Examples include caffeine, bright artificial light, advanced age, jet lag, and certain diseases.

Melatonin can also impact your metabolism, specifically through glucose regulation, or how you use and produce energy from sugar. Studies have suggested that melatonin supplementation may affect insulin sensitivity, glucose tolerance, and overall metabolic function.

Because melatonin is metabolized primarily in your liver and kidneys, individuals with impaired liver or kidney function may process melatonin more slowly, increasing the risk of side effects like daytime drowsiness. Age also affects your melatonin metabolism, making older adults more sensitive to prolonged effects.

For example, a study in the journal Cell Metabolism used both mouse and human models. It found that higher levels of melatonin can negatively affect the ability of beta cells to produce insulin. Beta cells are important for controlling blood sugar levels. 

The researchers also discovered that this effect is more prominent in individuals who have a specific gene variant in the melatonin receptor gene MTNR1B, which is associated with a higher risk of Type 2 diabetes. Interestingly, the study revealed that inhibiting insulin may have a protective effect against nocturnal hypoglycemia (low blood sugar levels at night), when melatonin levels are high but energy demands are low.

Another study, this time in Clinical Endocrinology, tested the effect of melatonin on glucose tolerance in postmenopausal women. After receiving either 1 mg of melatonin or a placebo, the women underwent glucose testing. Those who received melatonin had significantly reduced glucose tolerance and insulin sensitivity compared to the placebo group.

A Sleep journal study tested how melatonin use affects blood sugar control in healthy women. When participants took melatonin at night, their bodies became less responsive to insulin, causing blood sugar to rise higher and stay elevated longer. On average, their total blood sugar exposure was about 50% higher than normal, and their peak levels were roughly 25% higher.

These studies highlight that melatonin can influence your body’s metabolism and ability to regulate blood sugar levels, and that the effects can spill over into the next day. The research provides valuable insights into the complex relationship between melatonin and metabolic health. However, it’s important to remember that the effects can vary depending on the time of day and individual factors. 

Emerging research suggests that melatonin helps regulate the body’s inflammatory and immune responses, both of which are central to recovery and muscle adaptation. For fit, healthy people, that’s an important reason not to take extra melatonin. The body already produces its own precisely timed pulses of melatonin each night to coordinate inflammation and repair.

When you add melatonin from supplements, you can disrupt that natural rhythm, dulling the carefully sequenced inflammatory response that signals your body to repair and grow muscle tissue. Too much melatonin can shift the timing or intensity of those signals, potentially impairing the anabolic recovery phase that follows training.

In short: your body’s natural melatonin cycle already knows how to manage inflammation and recovery. Adding more doesn’t enhance the process, it risks blunting it.

There is a role for melatonin use in short-term sleep timing and rhythm challenges as long as the dose is a reasonable amount: 0.3 mg to 1.5 mg. However, there are people who regularly take supraphysiological doses in the 5 mg to 10 mg range, which is inadvisable. “Supraphysiological” means an amount well above and beyond what your body can naturally produce or process.

There is interesting literature on how taking melatonin could be helpful for seniors and those in certain disease groups, such as those affected by Alzheimer’s or certain cancers (again, as long as the dosage is reasonable). But for the rest of the population, the potential unwanted effects of long-term use, including hormonal disruption or hormonal imbalance, likely outweigh the potential benefits.

Several analyses of over-the-counter melatonin supplements have found that actual melatonin content can vary by as much as 347% from what's on the label. Some even contain undeclared serotonin, which could have unintended effects on mood and hormonal balance.

The decision whether or not to use melatonin in your personal sleep stack is therefore a personal choice, one that you should research carefully and make in consultation with your healthcare specialist.

Does the regular use of melatonin supplements lead to a decrease in the hormone’s effectiveness over time? Studies are inconclusive. If a person requires gradually higher doses to achieve the same sleep-inducing effects, this would be called melatonin tolerance and could lead to a potential cycle of melatonin dependence. 

Alternatively, abruptly discontinuing melatonin after prolonged use may result in rebound insomnia or sleep disturbances.

Some studies have shown that the long-term positive effects of taking melatonin for sleep appear to be limited. They find that after 12 months, the sleep of participants isn't measurably different from that of people who are taking a placebo.

If you've taken the hormone as a sleep aid for a long time and you want to quit melatonin, there is a safe way to stop taking melatonin: 

• Do it gradually. Tapering off will be less jarring to your system. 
• Ideally, you will also keep good bedtime habits.
• Manage the light in your environment. 
• Support your body with nutrients so it can make the right amount of melatonin (at the right time) on its own.

Another way to naturally support your rest and recovery at night is to switch to a melatonin-free sleep supplement. Look for a product that doesn’t contain melatonin, CBD, or sedatives. Your best options will even offer additional benefits by incorporating ingredients like glycine (of which sleep expert Dr Andrew Huberman is a proponent), L-theanine, GABA, and magnesium in carefully researched amounts.

For example, Thirdzy Rest & Recover Collagen contains all of these to support your body’s nightly recovery processes, including your muscle recovery.

By now it should be clear that while most people associate melatonin with sleep, it plays many other important roles in your body. And as with all hormones, there is a “Goldilocks” zone. You don’t want to have too much or too little, and you don’t want imbalances to last for extended periods of time. 

Fortunately, you have alternatives when it comes to the different types of sleep supplements, melatonin isn’t your only option. 

For example, maybe a magnesium powder or a collagen sleep aid would better help you meet your health goals. There are also superfood herbs that can promote a good night’s sleep. 

Your chosen supplement should fit easily into your routine without causing dependency or disrupting your hormone or metabolic health.

Remember, at the end of the day (pun intended), your needs are unique. Choose the product that will provide you with the most comprehensive approach to improving your own individual sleep quality, optimizing your overall health, and boosting your recovery potential.

Sleep tight,

Dr. Justine Luchini

Yes, melatonin can affect hormone levels involved in reproduction, sleep, and metabolism, especially when taken in high doses or long term.

Melatonin generally does not raise estrogen levels; in some cases, it may even have an inhibitory effect on estrogen production.

Melatonin can influence reproductive hormones by affecting the timing of ovulation and menstrual cycles, though its impact varies among individuals.

There’s limited evidence that melatonin increases estrogen in males; most research shows it may actually help regulate or lower estrogen levels.

Melatonin itself is a hormone, and while it can influence other hormones, it’s not classified as an endocrine disruptor like some environmental chemicals.

Excessive or prolonged use might disrupt the body’s natural hormone balance, particularly in individuals sensitive to hormonal changes.

Some people may experience side effects such as drowsiness, dizziness, headaches, or vivid dreams after taking melatonin.

Melatonin can suppress luteinizing hormone (LH), which plays a key role in reproductive function.

Melatonin doesn’t directly cause weight gain, but its effects on sleep and metabolism could indirectly influence weight management.