Melatonin is a hormone produced by the brain that helps regulate the body's circadian rhythms, or body clock. Levels of the hormone peak at night, and this association with sleep has lead many to use melatonin supplements as a remedy for jet lag or insomnia.
But melatonin has also been shown to increase inflammation of the airways in animal studies, which can make it harder to breathe. That prompted researchers to look at whether melatonin might play a role in worsening nocturnal asthma symptoms.
Rise in Melatonin Linked to Nocturnal Asthma Symptoms
In the study, published in the Journal of Allergy and Clinical Immunology, researchers followed seven people with nocturnal asthma, 13 with non-nocturnal asthma, and 11 healthy individuals. After establishing a normal sleep schedule for seven days, researchers took small blood samples every two hours from the sleeping patients on the eighth night and analyzed their melatonin levels.
The study showed that people with nocturnal asthma had the highest levels of melatonin and the biggest decrease in lung function during the night. Melatonin levels peaked at about 67.5 among nocturnal asthmatic people, 61.1 in non-nocturnal asthmatic people, and 53.5 in healthy people.
"For patients whose asthma worsens at night, we found that higher levels of naturally occurring melatonin are associated with impaired lung function," says researcher Rand Sutherland, MD, MPH, of National Jewish Medical & Research Center, in a news release.
"These findings suggest that melatonin naturally produced by people with nocturnal asthma increases inflammation in their airways, leading to worse lung function," says Sutherland. "Given that previous work has shown that melatonin promotes inflammation in the cells of both nocturnal and non-nocturnal asthmatics, any person with asthma should be cautious about taking supplements that would further raise their melatonin blood levels."