I have discussed this topic in my book. It was noted by Paul Eckman that simply frowning all day left him feeling poorly. Dr. Eckman is well known for learning how to read faces. He spent his entire career describing what muscles were responsible for displaying a specific mood and conducted experiments in how to read mood by observing the expressions on someone’s face. He and his colleagues noted that after spending a day displaying sadness on their faces, they actually felt sad. Simply expressing sadness on your face will change the way your brain is functioning.
Similarly, it has been noted in the literature, and also in my book, that botulinum toxin type A (Botox) injected into facial muscles has the potential to blunt feelings. Being unable to frown or smile, because of the botulinum toxin that was injected to reduce the appearance of wrinkles on the face, left subjects feeling blunted as well. Again a link between how we look and how we feel.
Now the authors of the study above find that living with someone who is depressed can make you feel depressed, especially if you are prone to moodiness yourself. So the old saying “smile and the world smiles with you, frown and you frown alone” isn’t completely true. It should read “smile and the world smiles with you, frown and you can make the world frown too.”
Just as it has been shown that frowning and looking sad can worsen your mood and being depressed can be contagious, the opposite is also true. If you smile, you will feel better and smiling is also contagious.