Focus, Work, and Irritability

When I work on a project for more than an hour or two, I start to become irritable. I start to experience frustration to the point of wanting to scream and/or cry. Does this happen to anybody else? Is it possible to bypass that wall? I hate having to take constant breaks, especially when it entails anxiously fixating on the project. However, it seems to be the only option; if I try pushing myself to continue, my quality of work begins to suffer. It's kind of like being hangry.

yes, i have exactly the same problem. usually i feel after about an hour that i have bitten off more than i can chew and i have to use all my willpower to at least try to finish a decent amount of work, if the project is too large to finish completly. maybe if we tried smaller increments of work? like, from one half hour to the next and so on?

My pdoc said today that it's not good to try to do something like that for hours and hours because you quickly reach a point of diminishing returns. It's actually most healthy for your brain and your mood to take significant breaks every hour. Like at least 15 minutes up to am hour. I find this hard to deal with because I tend not to be able to return from breaks so i just push myself to keep going and going for up to 18 hours if I'm cramming for a final or something. But by the end I'm probably not retaining anything and would be better off sleeping.