Yeah I struggle with the same thing, even conversations can tire me out. I think it’s because since our brain is bored by the task, it stops engaging entirely, leaving us with no energy or motivation to continue. I’ve noticed that the feeling usually goes away if I do something I like for 10 minutes, either by going on a walk or watching some Youtube. Maybe if we can treat this feeling as a signal for a break/reward, we’ll be less likely to avoid the task? Either way, I hope you’re doing well, and good luck!

Everytime I work on a big project even if it is for short time my brain crashes afterwards, and I feel I need to sleep most of the times I don't but I feel so tired for a while before I can do anything. 
It reminds me of the feeling you get after a hard therpy session.
Any suggestions? 

NUMO ADHDNUMO
ADHD

Power crash