Based on the experience of many who have posted here on NT, not resting will delay recovery until that time when one finally gives in and rests. The activity delays the start of recovery. I would be willing to suggest that the longer one pushes the limits, the greater the chance of some permanent symptoms. When the brain is under stress, it is under a chemical attack. The longer the chemical attack, the greater the risk of cellular damage. Plus, one can end up with severe depression and other psychiatric issues. PTSD comes to mind.