Ah... I've heard of that.Eh... No.Do you skip breakfast?Do you sunbathe normally?Eh?For example, a deficiency in serotonin.The thing they call the happiness hormone on TV all the time.But how would I know if I have enough or not...Exercise regularly?NoI used to. Lately, I've been eating it.I see. The symptoms of serotonin deficiency are as follows---