Sighing

I let a out a very audible world-weary sigh for my wife to hear after we dropped my daughter at daycare. She says "what's that?" And I took her literally and began to think what is sighing? Isn't sighing just a petulant or disgruntled form of meditation? Like meditation, there's deep breathing, but it's paired with a feeling of resignation that replaces the serenity of true meditation.