Most people with bipolar, like myself, don't shop for shopping's sake; it's because they want to take on a new project or make a major change in their life. I'd buy things like homebrewing supplies, a project car, or athletic equipment. It all either gets returned or starts sitting around a month later, when things get worse.

Sometimes, the projects you failed at eat away at you, daily proof that you are as big of a failure as you think you are, marking your failure as a person. When it's already hard to get out of bed, having to walk past hallmarks of your incompetence makes it even harder.

Rinse and repeat a couple times a year.

That's what mania is for me: a surge of confidence in myself, visible to others as pressured speech and hyperactivity, occasionally leading to irritability. It varies from person to person, though.