Can melatonin, a hormone, accelerate hair loss. Does it increase testosterone or lower it?
Where are you reading these things? Melatonin does not cause hair loss or have anything to do with testosterone other than both being hormones.
Some people have tried using topical melatonin to treat hair loss (likely based on this pilot study that came out in 2004), but that’s not a proven treatment and likely not going to give the results one is looking for.