Thanks for reply. Melatonin is produced by pineal gland so I've ment that I need to check its "natural occuring" levels in my body. I don't need melatonin pills. I found some "Melatonin test kits" made in USA but they all require to send saliva samples to laboratory. I want to find a way to do it completely by my own at home because I can't send samples from Russia to USA (it is said that samples must be fresh enough).