Psychoneuroimmunology is a field of science that studies how our thoughts, feelings and emotions affect how our body’s immune system works. It studies how our mind, nervous system and immune system work together. Our feelings, thoughts and behavior can influence our immune system, meaning that unhealthy habits can weaken our body’s ability to fight off germs and diseases. Psychoneuroimmunology helps us understand this connection a little better, so we can take better care of our health.