P.serine is not for sleeping. the other one melatonin is for sure. i get sleepy after taking melatonin. but not like " i gotta sleep now!" more of a sleepy feeling which is not that strong really. i live in denmark so i got melatonin from a danish co. and the P. serine was just online. i think P. serine is the most important of these two by the way. peace :)