"Mental exhaustion" refers to a state of being extremely tired or drained mentally, usually due to an excess of mental activity, stress, or emotional strain. Full definition
It's a state of emotional, physical and mental exhaustion caused by excessive and prolonged stress. (creativeboom.com)
But the addition of a teams best player and the excitement of playoffs can do wonders for mental exhaustion. (sbnation.com)
To the runner, the race is to be endured and concluded, if timed correctly, by a collapse in total physical and mental exhaustion at the finish. (firstthings.com)