I can speak from experience on this topic because I feel this way a lot, particularly when I'm stressed and/or not given ample time to recharge.

Are you an introvert? Because I am an introvert and if I'm not given at least a few hours a day to myself to recharge, I become hostile and irritable towards other people.

If you aren't an introvert than it could be simply stress causing this as other's on this thread pointed out.

Chances are though, you could be a fellow introvert who is being denied precious recharge time. If so, I would highly recommend putting more time aside for yourself to do introvert things.