6-hydroxy melatonin is primarily used in research studies focused on understanding the metabolism and biological activity of melatonin. It serves as a key metabolite in investigating how melatonin is processed in the body and its potential antioxidant effects. Researchers also utilize it to explore its role in regulating oxidative stress and its impact on cellular health. Additionally, it is studied for its potential applications in neuroprotective therapies and its influence on sleep-wake cycles. Its role in modulating inflammatory responses is another area of interest, particularly in conditions related to aging and neurodegenerative diseases.