protein shake keeps me awake?

[Alobar]

Is this normal? I checked the lable and there isnt any kind of stimulant in it (at least that Im aware of), but I've noticed if I drink it in the evening Im wide ass awake until like 3am (when I otherwise would normally fall asleep around midnight or 1am). It's not like Im wired like if I had a redbull or something. Im tired, but i just lay there not being able to sleep (which is usually never a prob for me)