What Causes Severe Fatigue While On Cymbalta And Clonazepam?

Nobody else seems to know. I am a 67 years female. I have extreme fatigue and have been experiencing a very bothersome problem. I can sleep 12 hours or more. I have energy at night and can go to bed from 2 to 5 am. But then I sleep, sometimes until 3 in the afternoon. I hate this and I am not getting anything done! I have had a sleep study test and it was normal. I do not take sleeping pills or anything like that and I do not have alcoholic drinks. I was diagnosed with brain lesions in 2012 and my neurologist took multiple tests to check for MS. There has never been a diagnosis of MS. But I do have other MS symptoms such as double vision, constipation, and it seems my balance is slightly worse. I am going crazy trying to figure this out. My doctors haven t been able to help. I take Cymbalta for depression and a little Clonazepam because I get seizures from anti-depressants. But this sleeping is something I cannot tolerate and don t understand.