I don't know how it took me so long to notice this.
When I'm working on an important project or something that I just want to finish and I start to feel tired (might be just boredom or lazyness), as I want or need to finish it I keep working, I will start to work slowly, spacing out and eventually start procrastinating, hoping that if I rest from the work a little I might be able to continue (it never works)
Then one day I was working in this tired mode and decided to take a nap, then trying to fall asleep, trying to fall asleep, trying to... wait... if I'm "tired" Why is it so hard to fall asleep?
I just stand up, keep working and didn't feel tired.
So, I start repeating this, whenever I start feeling "tired", go take a nap and then 2 things can happen, I fall asleep (I was actually tired) or I can't fall asleep so stand up and keep doing whatever I was doing.
I don't know if this might help someone as everyone has different sleeping habits (I have done poliphasic sleep and I seem to do better with it, but is to hard to fit it in a normal schedule) so I'm just sharing