WSJ: Genuine smiles help your heart
“We smile because we feel not threatened,” says Dr. Pressman. Over time that message evolved so the muscle activity involved in a smile sends a message to the brain signaling safety, which could translate into lower heart rate and stress levels. Dr. Pressman is currently researching how smiling affects certain stress hormones, such as cortisol, and oxytocin, which is sometimes called the trust hormone. “We’ve already seen it with heart rate; we’re hoping to see it with these other stress levels in the body,” she says.