Melatonin supplements, widely used to treat insomnia, may serve as a safe addition to chronic pain management and help reduce the need for stronger pain medications, according to researchers at the The University of Sydney. The findings were published in the journal PAIN.

The researchers found that melatonin can reduce chronic musculoskeletal pain, with an effect comparable to that reported for some commonly used pain relievers, including opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), and paracetamol (acetaminophen). According to the authors, chronic musculoskeletal pain affects up to 47% of the global population, suggesting that an inexpensive and widely available treatment could have a meaningful impact on patient care.

The study analyzed data from 2,028 adults enrolled in 23 randomized controlled trials conducted in the United States, Russia, Brazil, Egypt, China, and several other countries. Participants included people with chronic low back pain, osteoarthritis, fibromyalgia, as well as patients recovering from surgery, including joint replacement procedures and spinal operations.

On average, melatonin reduced pain intensity by approximately 9 points on a 100-point pain scale. In the highest-quality studies, the reduction approached 10 points—an effect similar to that observed with several commonly prescribed analgesics.

In addition to reducing pain, melatonin also improved sleep quality, an important finding given the close relationship between chronic pain and sleep disturbances.

"For many patients, pain does not exist in isolation—it is closely linked to poor sleep. Melatonin appears to address both problems simultaneously, making it particularly valuable for people living with chronic pain," said the study's lead author, Kanchao Wu.

In most of the studies, participants with chronic pain received between 3 and 10 mg of melatonin, with 3 mg taken before bedtime being the most common regimen. For postoperative pain, doses typically ranged from 5 to 6 mg. However, the researchers found no clear relationship between dose and treatment effect, meaning the optimal dosage has yet to be established.

The authors emphasize that melatonin is generally well tolerated, is not associated with dependence, and typically causes only mild side effects, such as nausea, dizziness, and headache. However, they do not recommend using it as a replacement for standard pain medications.

Instead, the researchers suggest that, after consultation with a healthcare professional, melatonin may be considered as part of a comprehensive treatment plan, particularly for patients who experience both chronic pain and sleep disorders.