The study found that once facial muscle movements as a smile will resulted blood supply to the brain was temperature is reduced and will cause feel comfortable and relaxed as opposed to making static face and frown eyebrows, That movement of facial muscles to make the brain temperature is higher, and caused discomfort.
In addition, while we smile and then heart to beat slower, blood pressure decreases and systems in the body to relax, adrenal glands to work less and epinephrine is hormone of the strain was less excreted as well. Smile thus helps reduce stress.
We are happy and then smile or first smile and then happily, cause scholar must make a thorough study on this subject and the result will be found to have both. That is when we feel happy, we are facial expressions with a smile but there are some people who like to suppress their emotions. When he is happy then will try to force the expression to be serious. That use of facial muscles and lose a lot of energy and thus can not be fully happy.
In contrast, even though we do not feel happy but when smile a few minutes, we will feel good and happy as well.