What Is Melatonin?

The Body's Natural Sleep Hormone

Person lying awake in bed, struggling to fall asleep

Verywell / Nez Riaz

Melatonin is a natural hormone produced by the brain's pineal gland; it is also present in other areas of the body such as in the gastrointestinal tract. Melatonin is secreted at night, during which time it helps you fall asleep.

What Is Melatonin?

Melatonin is commonly referred to as the “sleep hormone.” It is produced by the brain and it's responsible for the timing of your circadian rhythm (also known as your sleep-wake cycle), and plays an integral role in helping you fall asleep, stay asleep, and wake up.

This article covers the definition of melatonin, how melatonin is produced in the body, what inhibits its production, and information on melatonin supplements.

How Melatonin Is Produced in the Body

The production of melatonin is influenced by light. The retina (a layer of tissue inside of the eye) processes light, and transmits this energy to the pineal gland in the brain. The pineal gland then secretes melatonin into the bloodstream. Melatonin is carried from the brain to the rest of the body via circulating blood.

Think of melatonin as turning on your body's "night mode." When cells in the body aren't exposed to melatonin, they're in "day mode."

Melatonin is responsible for making us tired at night and less tired during the day. Melatonin production is triggered by light; so, the more light we are exposed to, the less melatonin is secreted, whereas darkness triggers melatonin production.

Melatonin levels also have a seasonal rhythm, with higher levels in the fall and winter, when nights are longer, and lower levels in the spring and summer, when nights are shorter.

Impact of Melatonin on the Body

The primary role of melatonin that has been studied in humans relates to sleep and wakefulness. Nocturnal melatonin levels peak between one and three years old, plateau throughout early adulthood, and steadily decline in later adulthood.

For example, a 70-year-old individual will only have a quarter of the melatonin amount that a young adult has. The fact that melatonin decreases as we age could be one of the reasons that newborns and toddlers require many more hours of nightly sleep compared to elderly adults.

But melatonin may play multiple roles in humans, many of which are not fully understood. Research supports that melatonin has anti-inflammatory, antioxidant, and anticoagulant (clot-preventing) properties.

How Melatonin Affects Health

Melatonin actually has quite a significant link with mental health. Since melatonin regulates your circadian rhythm and sleep, melatonin deficiency can cause sleep problems such as insomnia.

Sleep disorders are linked with other health conditions such as:

Some mental health disorders are correlated with insufficient melatonin production, and therefore, cause disrupted sleep. Such conditions include major depressive disorder (MDD), bipolar disorder, anxiety, and schizophrenia.

It's still not understood whether circadian rhythm disruptions cause mental health disorders or vice versa, but research suggests that circadian disruption may exacerbate symptoms in people who are already predisposed to developing a mood disorder. Resynchronizing circadian rhythms in people with mood disorders can help improve symptoms.

Melatonin Deficiency 

The body is expected to produce sufficient amounts of melatonin for sleep. Unfortunately, modern lifestyle factors can contribute to insufficient melatonin production. This can lead to problems falling asleep at night and waking up in the morning, as well as a feeling of tiredness throughout the day. Listed below are major factors that play a role in melatonin deficiency.

Alcohol

Drinking alcohol before bed can cause difficulties with falling asleep and staying asleep. Chronic alcohol consumption actually decreases melatonin production.

In addition, studies show that people with alcohol use disorder commonly experience sleep disorders such as insomnia, circadian rhythm sleep-wake disorder, restless legs syndrome, and more.

However, the connection between alcohol use disorder and sleep disorders is likely due to multiple factors such as genetics and underlying mental health conditions (like depression) as well.

Blue Light

Your electronic devices—such as your phone, laptop, and television—emit a blue light that actually stimulates your brain, blocks melatonin, and interferes with sleep. To help block out some of this light when you do use your devices, you can try wearing blue-light-blocking glasses. But limiting your exposure to blue light is important, too.

A good rule of thumb is to turn off all electronics at least an hour before bed.

Caffeine

If you consume caffeinated beverages such as coffee, tea, soda, or energy drinks late in the day, the caffeine contained in them can reduce levels of melatonin in the body. Caffeine has a half-life of about four hours—meaning it'll talk your body eight hours to fully rid itself of the caffeine.

It's recommended that the average person stops drinking caffeine by 12 pm in order to obtain the best night's sleep.

Shift Work

If you work a night shift, you might find that it's harder to get a good night's sleep. That's because daylight decreases melatonin levels, so you're less likely to get a good night's sleep if you're trying to stay awake at night and sleep during the day.

One study found that a group of night-shift workers experienced almost 34% less melatonin production than day-shift workers over a 24-hour period.

Jet Lag or Time Change

Your circadian rhythm is your body's internal clock that helps you go to sleep and wake up. However, your environment influences your circadian rhythm as well. For this reason, flying to another state or country with a different time zone can lead to difficulty sleeping.

Say you travel to a country that is five hours ahead of your home time zone. When it's 10 pm at your destination, your internal clock will still feel like it's 5 pm, at least until you adjust. But you will likely struggle to fall asleep. Your internal clock will tell you to stay awake, while your melatonin production is trying to get you to fall asleep because it's dark outside. This is what causes jet lag.

How to Boost Melatonin Naturally

There may be ways you can increase your levels of melatonin, leading to a better night's sleep. Try:

  • Eating melatonin-rich foods: Some foods—like eggs, fish, and nuts—are naturally high in melatonin and may help you get a better night's sleep.
  • Spending time in sunlight: Exposure to sunlight plays a vital role in regulating your circadian rhythm. Ensure you're getting adequate light exposure during the day (decreasing melatonin) so you're sleepier at night.
  • Taking a hot bath or shower before bed: Relaxing with a hot bath or shower can actually reduce the production of cortisol (a stress hormone) in the body and trigger melatonin production.

Melatonin Supplements

The melatonin pills you see in the grocery store or pharmacy are made synthetically. They're often used to help people get to sleep, ease the symptoms of jet lag, and even lessen anxiety before or after surgery.

Though melatonin supplements may be helpful for sleep, keep in mind that it's best to consult with a doctor about any chronic sleep issues (lasting one month or longer) that you're experiencing.

Side Effects of Melatonin Supplements

Short-term use of melatonin supplements is generally considered safe; however, there isn't enough research yet to discern melatonin's long-term effects.

Side effects of melatonin use include headaches, nausea, dizziness, sleepiness, and nightmares.

In rarer cases, there are more severe effects of melatonin including mild anxiety, feelings of depression, tremors, abdominal cramps, confusion, or hypotension (low blood pressure). Be sure to talk to a doctor if you experience these or other side effects.

Warnings and Interactions

It's important to know that melatonin may interact with medications or supplements you're currently taking. Consult with a doctor before taking melatonin if you're already on medication (specifically if you are taking a medication for epilepsy or a blood-thinning medication).

Talk to a doctor before taking melatonin if you are pregnant or breastfeeding—there is a lack of research on the potential health effects of melatonin on unborn children or children who are breastfeeding.

Additionally, it's best to consult with a doctor before giving children melatonin. It's also advised that elderly people are cautious when taking melatonin because they may experience longer-lasting effects.

Finally, melatonin is considered a dietary supplement by the Food and Drug Administration (FDA), which means it's not regulated as closely as prescription drugs. This is another reason it's best to talk to a doctor prior to taking any supplements.

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Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Kristen Fuller, MD
Kristen Fuller is a physician, a successful clinical mental health writer, and author. She specializes in addiction, substance abuse, and eating disorders.