Yes, Melatonin is great for helping to sleep, but in some people it can trigger depression.
just give it a few days, and it will pass...
see if you can lower your dose, or get a time release...
the body creates dopamine, and between these two, it is your day/night cycle.
the tricky thing is to balance the dopamine and melatonin.
The interesting thing about people who have high melatonin, they may be more depressed, but they also have less cancers and health problems to actually be able to complain about,
Melatonin has a great deal of healing properties.