When you are in bad mood do you affect people around you?

I have this experienced that whenever my co-workers is in bad day or bad mood she affects everyone around here making people get irritated and she even get easily irritated to everything making our workplace so uncomfortable. I also experiences it with my self that when I am in bad mood I easily get irritated and that affects those people around. Is it normal or I'll just been sway because I just did saw it with my co-worker and also because it is the environment I've been part of?