Can someone explain why overwork kills people? I'm curious, maybe there's a way to work 70 hour weeks without harming your health? (I.e possibly overwork is cor

Can someone explain why overwork kills people? I'm curious, maybe there's a way to work 70 hour weeks without harming your health? (I.e possibly overwork is correlated with lack of sleep / exercise, which are the real dangers, not the work itself).