overwork

over|work /'oʊvə^rw'ɜː^rk/ (overworks overworking overworked)
[VERB] V, V n
If you overwork or if someone overworks you, you work too hard, and are likely to become very tired or ill.
He's overworking and has got a lot on his mind...
He overworks and underpays the poor clerk whom he employs.
[N-UNCOUNT]
Overwork is also a noun.
He died of a heart attack brought on by overwork.
● overworked [ADJ]
...an overworked doctor.