Educational reference
About this symptom
Fatigue in mental health contexts is not simply tiredness after exertion. It is a persistent depletion that rest does not reliably relieve, and it often arrives without a proportionate cause.
People describe effort becoming disproportionate to task: showering, replying to a message, or leaving the house taking energy that would once have been unremarkable. It frequently combines with slowed thinking, so both physical and mental effort feel heavier.
Fatigue is one of the least specific experiences in medicine. It occurs in depressive conditions, anxiety, and following trauma, but equally in anaemia, thyroid conditions, diabetes, sleep apnoea, chronic infection, medication effects, and simple sleep deprivation. That breadth is why assessment usually includes physical health rather than assuming a psychological cause.
Persistent unexplained fatigue is worth investigating in its own right, whatever else is happening.