I believe it's effective.
Seems to work. TL;DR - It is hard to test the effectiveness of this kind of product as the difference it makes is quite subtle, however over the medium term (a few weeks) this product seems to make a difference to my quality of sleep. I take one pill daily just before I go to bed, and take it with half a banana, or a small bowl of low sugar muesli. I've had no side effects that I'm aware of. I've been advised by my doctor that there's not much point taking melatonin that isn't slow release, as it doesn't stay in one's system for long in that case.