Shopping is an anytime sport for many of us, and playing the game during your lunch break seems like an efficient use of time. Not so fast. There are two factors that could cause you to spend more when squeezing in a trip to your favorite store: time and stress.
One hour isn't enough time to thoroughly shop, and it's easy to end up with more goodies than you wanted — the decision to take one of each instead of narrowing down your selection doesn't do your wallet very much good. And releasing the stress from your Monday morning meeting by swiping your credit card isn't a release at all when you realize that you've spent more than you can afford.
You could save shopping for after-work hours, but the same issues still exist. Save your shopping for the weekend when you have time to weigh spending decisions and aren't using shopping as an emotional outlet.