Waking up at night..

Dominika • Mia was born on the 3rd of June 2015<3
I'm almost 22 weeks pregnant and I keep waking up at night.. Is anyone else experiencing this? Is there a reason why it's happening.. Like I wake up, and I don't feel tired at all, and when I eventually fall asleep again then wake up after that I feel soo tired😥 and I'm still in school, it's really hard cause I walk into it half dead lol