Your arms, your face and your posture were talking the whole time you thought you were being quiet.

There is no way to opt out of communicating in a room. Crossed arms, a flat face, a body angled toward the door: all of it is being read, and usually more trusted than whatever you say later. Most of it is not about the room at all, just tiredness. The problem is that nobody can see the reason, only the signal.

Check your body once in the middle of the next conversation you care about. Unfold, turn slightly toward the person, and notice whether the tone in the room shifts.