ps4 turns on by itself

I noticed it todaym its never happened before, at least i didn´t see it. Today i noticed my ps4 was on, i thought somebody accidentally turnet it on, so i swithched it off and that´s all. But then, a while ago, suddendly it turned on, and i didn´t touch anything :S I was searching a little and read some people with the same issue, but i don´t know if it´s something "normal" or not. Thank you.