I get that too. I feel really tired all the time, where I could sleep for days if I could get a chance! I also have TERRIBLE dizzy spells lately. I am sure that has a lot to do with the oxygen not circulating very well at this point.
If I find out anything I will let you know....
Hasty horse who drinks too much water gets belly ache
Early on I was able to sleep a full night, take long naps during the day and then sleep at 9pm that night. If I'm out and about for too long I get very weak and tired. If I move too quickly I also get lightheaded and dizzy. I also get that way if I don't eat enough. You'd think I would be done eating for a bit, but two hours later I'm faint and my stomach is growling so I have to snack again.