Study: Increasing melatonin use raises concerns

Contents

STUDY AT A GLANCE

What is this study about?

This study reports on the growing use of melatonin as a sleep aid by adults in the United States.

Why is this study important?

Many adults have trouble falling asleep or staying asleep. The discomfort or anxiety that may occur from testing positive for an inherited mutation or being diagnosed with cancer can worsen sleep difficulties. Sleep issues may also develop as a side effect of cancer treatment, cancer prevention or menopause.

Melatonin has been available as an over-the-counter sleep aid for many years. The supplements are sold over the counter (without a prescription) in drug stores and supermarkets alongside vitamins and herbs. Melatonin pills and gummies are available in doses ranging from 1.5 mg to 60 mg. 

Little is known about how people use melatonin as a sleep aid and there is limited data on long-term or high dose use. In this study, researchers looked at melatonin use among a large group of people in the United States for almost two decades . The data collected indicates that there is a need for better awareness of the safety and side effects of melatonin use among people who use melatonin.
 

Melatonin

Melatonin, a hormone that affects brain function, has gained popularity in the U.S. as a sleep aid. It helps manage the body’s circadian rhythms—our internal clock that responds to light and dark and lets our bodies know when it’s time for sleep. Doctors sometimes recommend melatonin to travelers to prevent or manage jet lag. Some evidence shows that melatonin can minimize delayed sleep-wake disorder, a condition that causes sleep delays of two or more hours. Studies of melatonin for insomnia or general sleep disturbance have been inconclusive.

Like other dietary supplements, melatonin is unregulated by the U.S. Food and Drug Administration. Manufacturers are not required to meet criteria for safety or effectiveness in preventing or treating a health concern, in this case, difficulty sleeping. Likewise, melatonin pills are not tested to ensure they contain the dosage listed on the bottle. Consumers decide and choose the brand, dose and use schedule.

While melatonin is considered to be mostly safe by many experts, it can cause short-term side effects, which are usually mild and may include headache, dizziness, nausea and sleeplessness. Taking melatonin with other drugs may not be safe, and long-term side effects are unknown. For these reasons, researchers need to learn more about trends in melatonin use. The findings from this study may encourage further research on the benefits and risks of melatonin as a sleep aid.

Who participated in the study?

This study used data from the National Health and Nutrition Examination Survey (NHANES), a long-running, government-led study of population health. The study is designed to capture a point in time. The people surveyed were asked about their use of dietary supplements in the past 30 days and the dose used.

• A total of 55,021 adults ages 20 and over were included in the sample.
• Data were collected yearly from 1999 to 2018.
• The number of respondents in each survey year ranged between 4,865 and 6,214.
• The average age of participants was 47.5, with slightly more women (52%) than men participating.
• Around 40% of those who reported taking melatonin were between the ages of 45 and 64. The remaining 60% fell evenly into the 20-44 and 65+ age groups.

Study findings

This study looked at the percentage of adults in the United States who take melatonin and how many of them take more than the typical recommended dosage.

The study found that melatonin use among the general population is growing.

• This growth spans different ages and genders.
  • Melatonin use increased from 0.4% between 1999 and 2000 to 2.1% between 2017 and 2018.
    • Five times as many people took melatonin in 2018 as did in 2000.

The study also looked at the number of people who take a high dose of melatonin. A high dose is defined as more than the typical recommended dose of 5 mg.

• The use of higher doses of melatonin was extremely low, but it more than tripled—from 0.08% between 2005 and 2006 to 0.28% between 2017 and 2018.

The study authors point out that there is little evidence to support the use of melatonin as a sleep aid. They express two specific concerns about safety: 

• Melatonin use can cause reactions (“adverse events”).
• Melatonin supplements are unregulated.

Strengths and limitations

Strengths

• The research relied on data from NHANES, an established, large-scale survey that looks at health status and behaviors at a point in time. NHANES is conducted by the National Center for Health Statistics and the Centers for Disease Control and Prevention (CDC). Each year, study interviewers survey people in 15 randomly chosen U.S. counties. The findings from these surveys have provided information on important health topics, including the prevalence of high blood pressure, baby and child growth rates, and exposure to environmental hazards.
• The study looked at almost 20 years of data.
• NHANES interviewers spoke with participants in their own homes. Interviewers saw the supplement pill bottles and confirmed the dosage information for 94% of the participants who said they took melatonin.

Limitations

• This study relied on people to self-report their use, which can be a limitation, but it was less limiting in this study because researchers had access to most respondents’ pill bottles.
• The researchers were not able to learn about melatonin use by racial or ethnic groups because the number of people in some subgroups who take melatonin was too small to be statistically significant.
• Dosage information was only available for people who were surveyed after 2005.
• The researchers did not provide data on the reasons why participants took melatonin because this information was not available for all study years.
• The study did not include findings on whether the people who took melatonin experienced any side effects and whether the side effects varied by dosage.
• This study did not look at melatonin use among people with cancer and those at high risk for cancer; these subgroups may experience sleep difficulties for different reasons.
• The study reported on data before the start of the COVID-19 pandemic in 2020 so it does not capture any trends that may be occurring as a result.

Context

This study is the first to document the increase in melatonin use among the general population. The overall use of dietary supplements also increased between 2009 and 2018, which suggests more openness to supplementation in the U.S.

The variability of melatonin pill content is concerning, and consumers may not know what they are taking. Studies have shown that these pills sometimes contain a much larger dose than described on the label—as much as 478 percent more. One study found 26 percent of melatonin pills contained serotonin, a controlled substance.

Research on melatonin as a sleep aid continues. It is also the subject of ongoing research on the prevention and treatment of diseases, including cancer and COVID-19.

Conclusions

More people take melatonin as a sleep aid, and a small but growing subgroup takes it in larger doses. This increasing use raises concern because:

• research has yet to show that melatonin works as a general sleep aid.
• people who take melatonin may not understand how to use it safely.
• melatonin is available over the counter so people can make decisions about when and how much to take without consulting a doctor.
• melatonin supplements may contain more melatonin than the label suggests.
• melatonin can cause side effects or interact with other drugs.
• the long-term effects of melatonin have not been studied.

What does this mean for me?

If you take melatonin or are thinking about taking it, you are not alone. Yet, there is still a lot we don’t know about this supplement. While melatonin may help travelers with jet lag, research has yet to show its benefits as a general sleep aid.

• Generally, it is advised to talk with a health care professional before taking any dietary supplement.
• Let your doctors know if you are already taking melatonin. Talk with them about why you are taking it, how long you have been taking it, how often you take it, and at what dose. Make sure they are aware of all of the other supplements or medicines you take.
• If you are interested in melatonin, ask your doctor before taking it.
• If you are having trouble sleeping, talk with your doctor about what you are experiencing, and the possible causes of sleep trouble. Make sure you report any changes in your health and well-being. Trouble sleeping may be a sign of other health issues.
• Talk with your doctor about other medical or lifestyle options to improve sleep.
• Ask your doctor for a referral to a sleep expert.

The National Center for Complementary and Integrative Health offers more information on melatonin on its website.

The American Academy of Sleep Medicine maintains the public-facing website SleepEducation.org, which includes a section on finding a sleep center by location. 

References

Li J, Somers VK, Xu H, Lopez-Jimenez F, and Covassin N, Trends in use of melatonin supplements among US adults, 1999-2018. Journal of the American Medical Association 2022; 327(5):483–485. Published online February 1, 2022.

Melatonin: what you need to know. National Center for Complementary and Integrative Medicine. Accessed March 2022. 

Cintron D, Lipford M, Larrea-Mantilla L, Spencer-Bonilla G, Lloyd R, Gionfriddo MR, Gunjal S. Farrell AM, Miller VM, and Murad MH, Efficacy of menopausal hormone therapy on sleep quality: systematic review and meta-analysis. Endocrine 2017 Mar; 55(3):702-711.

Erland LAE and Saxena PK. Melatonin natural health products and supplements: Presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine 2017; 13(2):275-281.

Jafari-Koulaee A and Bagheri-Nesami M, The effect of melatonin on sleep quality and insomnia in patients with cancer: a systematic review study. Sleep Medicine 2021 Jun; 82:96-103.

Longgang Z, Tyson N, Liu J, Hebert J, and Steck S, Trends in dietary supplement use among US adults between 2009 and 2018. Current Developments in Nutrition 2021 Jun; 5(2):701.

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

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posted 4/14/2022