Melatonin Unit Converter

Melatonin is a hormone that regulates your sleep-wake cycle. It rises in the evening as darkness falls, peaks between 2:00 and 4:00 AM, and drops to low levels during the day.

A blood test measures circulating melatonin to assess whether your body is producing it in the right amounts at the right time. Because levels change dramatically over 24 hours, the timing of the blood draw is critical to interpreting results.

Melatonin also acts as an antioxidant and plays roles in immune function, metabolism, and reproductive health beyond its well-known sleep effects.

Melatonin is primarily produced by the pineal gland in the brain, which converts serotonin into melatonin in response to darkness. The gastrointestinal tract also produces large amounts that act locally, and smaller quantities are made in the retina, skin, and immune cells.