What Is Melatonin? The Role of a Sleep Hormone to Treat Insomnia

Hormone Has Role in Circadian Rhythms, Jet Lag, and Insomnia

Melatonin is sold as an over-the-counter sleep aid, but side effects may occur with the use of this hormone to treat insomnia and jet lag
Melatonin is sold as an over-the-counter sleep aid, but side effects may occur with the use of this hormone to treat insomnia and jet lag. Getty Images

What is melatonin and how does it help to aid sleep when insomnia occurs? What are the potential side effects of melatonin use? Melatonin is a naturally occurring hormone that may be effective in treating some sleep problems including jet lag, insomnia, and circadian-rhythm sleep disorders. Learn about this sleep aid and whether it is right for you.

What Is Melatonin?

Melatonin is a hormone that is secreted by the pineal gland, located more toward the back of the brain above the cerebellum and an area called the third ventricle.

Melatonin is produced from the amino acid called tryptophan and can be found in the blood as well as in the cerebrospinal fluid that bathes the brain and spinal cord. As a hormone, it conveys signals to other organs and seems to help regulate the circadian rhythms of the body. Melatonin production decreases as a person gets older.

Melatonin is often sold as a sleep aid and may be included as an ingredient in multiple over-the-counter formulations. It is available in lower doses (often 1 to 3 mg), but some pills may have doses as high as 5 or 10 mg. It is the only unregulated hormone available for purchase in the United States.

Melatonin’s Role in the Circadian Rhythm

The circadian rhythm is the body’s natural pattern of physiological and behavioral processes that are timed to a near 24-hour period. These processes include things like the sleep-wake cycle as well as variations in body temperature, blood pressure, and the release of other hormones.

Melatonin levels increase after the onset of darkness and peak in the middle of the night between 11 PM and 3 AM. It is sometimes called the "nighttime hormone" or the "sleep hormone." Melatonin seems to promote sleep and can influence the timing of the sleep period.

Melatonin to Treat Sleep Problems

Melatonin may be effective in treating circadian rhythm disorders in which the desire for sleep is disrupted in its timing, resulting in difficulty falling asleep (insomnia) or inappropriate sleepiness.

There are many common conditions that may be helped, such as:

Not everyone benefits from melatonin use, and the dose and timing of the medication administration are important considerations.

What Are Common Side Effects of Melatonin?

There are many potential side effects of any drug, including hormonal supplements like melatonin. Although you would be unlikely to experience most side effects — and you may not have any of them — some that may commonly occur include:

  • Stomach cramps
  • Decreased alertness
  • Amnesia (memory loss)
  • Chest pain
  • Circadian rhythm disruption
  • Confusion
  • Cramping
  • Daytime fatigue
  • Transient depression
  • Diarrhea
  • Dizziness
  • Drowsiness
  • Hallucinations
  • Nightmares
  • Headache
  • Hormone changes
  • High blood sugars
  • Low blood pressure
  • Increase eye pressure
  • Irritability
  • Mood changes
  • Nausea
  • Vomiting
  • Paranoia
  • Pruritus (itchy skin)
  • Seizures
  • Tachycardia (rapid heart rate)
  • Taste disturbance

Melatonin is not regulated as a drug and is available over-the-counter, but you should consult with your doctor to ensure that it is appropriate and safe to use to treat your sleeping difficulties. Caution is recommended when using melatonin among children and pregnant women.

If you have difficulty with chronic insomnia, speak with a sleep specialist about other treatments that may be effective for you, including cognitive behavioral therapy for insomnia (CBTI).

Sources:

Brzezinski, A et al. "Effects of exogenous melatonin on sleep: a meta-analysis." Sleep Med Rev 2005;9:41.

"Melatonin." Epocrates Rx Pro. Version 16.6, 2016. Epocrates, Inc. San Mateo, California.

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