Boffins from Ohio University proved that sweets are able to bring down the quantity of cortisone quickly and effectively, even if for a short time only.
Cortisone is a hormone participating in generating response to stressful situations. It means that the behavior of people who have just eaten some sweet goodie is apt to become quieter and friendlier even towards absolute strangers.
Experiments involving artificial sweeteners failed to produce the same effect.
So if you feel depressed, irritated or anxious, treat yourself to a sweet.