What is interesting about this symptom is that it is not directly associated with other symptoms (lack of motivation, sleep disturbances, etc) that one would associate with it.
It seems to be something of it’s own.
That is, the symptom has been shown to outlast any extension of rest the person might have. Feeling “drained” most of the time for we human would mean, physiologically anyways, that we need rest. Or more rest. However, even with excessive rest the person can remain in a state of increased tiredness.
So, imagine a day where you worked from sun up to sun down or perhaps one of the last days you felt completely exhausted at the end of the day. As soon as your head hit a cushion you were out cold.
But when you awake the next day, you felt the same.
As if you received no sleep.
the person tires easily.
the person is tired when waking up. Any sort of rest does not seem to alleviate the feeling of tiredness.
the person becomes too tired to do anything. Without extreme external motivation the person may succumb to their fatigue however long it is present.