I've never noticed that happening. Are you sure it's that caffeine in coffee (in other words do you take it black or add sugar and creme - either one of which could also be responsible for a downturn in mood). Sugar and milk products are some of the most common latent allergies and latent allergies can cause depression. I just wanted to make sure you knew that so you can keep an eye out. I hope you figure out what's causing this.