Mental illness is a real physical, mental, and emotional ailment. Some symptoms of illness include inappropriate behavior.
Personally, I become annoyed more easily because of bipolar. My children sometimes whine or demand things, and my hairs rise on the back of my neck. Now I have a choice about what to do: act or react. I can choose to yell at them, ignore them, or prompt my children to ask nicely. The okay choice is to ignore it, but that won't help my children improve in the long run. The better choice is to address my children's misbehavior. Sometimes, it's best to walk away for a moment.
I sometimes use Recovery spots like "it's average" for children to misbehave, or to "excuse rather than accuse."
So often people will shop, use sex, use drugs, gamble, play video games, overeat, or watch TV to bury the problem. None of these actions truly help. And mental illness is not an excuse to fall into addictions.
Mental illness needs to be faced head on. Take care of your body; pray for help; talk to someone. There are many healthy coping techniques out there. Find what works for you.