No one needs to tell us that exhaustion distorts reality, heightens emotions, and makes us generally hard(er) to live with. So it makes no sense to view the world through a lens of exhaustion. And while we may not have the luxury of putting ourselves to bed for a much-needed rest, we do--I hope--have enough life experience to know when to call it a day, even if that day's just begun.
We can, when necessary, show up, go through the motions, phone it in--whatever you'd like to call it. The brain and the soul can rest while the body keeps us on this side of truancy.