When you’ve spent an entire day resting and doing nothing, get to bed at a sensible time, then wake up feeling exhausted, like you need to sleep for hours and hours.
That’s chronic fatigue.
It’s not ‘feeling tired’, it’s not ‘feeling sleepy’. It’s struggling every day with utter exhaustion, and still dragging yourself out of bed to get to work.
Fatigue is not the same as being tired, pass it on.