Extreme Sleeping side effect

I’ve been on Effexor for a while (a couple years) but my partner has brought it up to me that I sleep a lot…like a lot. On average I sleep 12 hours a night with a lot of naps which can total up to another 2 hours. So we’re talking 14 hours total a day. Has anyone experienced this? I’ve relied a lot on energy drinks to even stay awake. Not to mention motivation in school (as I’m a student) has reached an all time low. I’m worried about quitting Effexor as the withdrawal symptoms are brutal. Any advice? Should I go to my GP?