Psychologists have long thought that the simple act of smiling actually makes you feel better. Now scientists have reported to the British Psychological Society that if you cannot frown and put on an angry or sad expression that you might not actually feel as angry or sad.
They tested one group of patients who had recently received BOTOX for their frown muscles against another group who had not received BOTOX. The BOTOX group had less brain activity when they tried to put on an angry expression than the non treated group.
So it is probable that facial expression has an effect on mood as well as the other way around. This improvement in mood will likely only be effective while the BOTOX remains effective.