A good workout usually leaves the body tired but settled. Breathing slows, muscles relax, and the mind feels clearer. But when exercise starts to overstimulate the nervous system, the opposite happens.
There is a restless energy that lingers. Sleep becomes harder. The body feels “on edge” even hours later.
This happens because intense or prolonged workouts increase cortisol, the stress hormone. When cortisol stays high, the body struggles to switch into recovery mode. Instead of feeling restored, it stays alert.
A study from the National Institutes of Health (NIH) explains how chronic high-intensity training can disrupt hormonal balance, especially cortisol rhythms
