Its likely because your not used to it, and you get a withdrawal afterwards. I struggle to sleep after having alcohol. If ive had one too many I get the spinning room ride and cant sleep. And one other thing when drinking is pace yourself. if your having 3-5 in an hour, perhaps have 2 in an hour, and maybe something a little different? Some drinks sit badly on people. My friend and jagerbombs, they dont mix lol.