I'm wondering this and trying to work out what is simple tiredness, and what is caused by my chronic illnesses or other stuff. I mean, in one way they are entangled completely but to see what other people are like.
After sleeping from 1am to 6am last night, I did my volunteer shift at a food bank and I've honestly been so wiped out for the rest of the day. It is just 2.5 hours long 
and making sandwiches, so standing up which I do find difficult so I get that but it feels COMPLETELY pathetic. I stayed an extra 15 mins to finish what I was doing.
My brain is completely blank. I cannot think properly in terms of organising or problem solving or tackling tasks - it's just a stream of consciousness of thoughts floating by. So, it's kind of easy to write this post because it's not mentally taxing, but I can't do anything productive that requires thinking through steps. I know I need to do stuff but it's so overwhelming. I l did lie down for half an hour but didn't sleep, as trying to get to bed at 10.30pm after I take last medication. Hoping to get a longer block of sleep tonight.
How do you feel energy wise if say half your week you are on 4 or 5 hours sleep? I shouldn't be this useless should I?
My ferritin and folate are really low and wondering if this is partly why.