Read the dictionary definition of drained. All definitions for this word.
1. drained of electric charge; discharged
1. a dead battery
2. left the lights on and came back to find the battery drained
2. emptied or exhausted of (as by drawing off e.g. water or other liquid)
1. a drained marsh
2. a drained tank
3. a drained and apathetic old man...not caring any longer about anything
3. very tired