Some researchers suggest that loneliness and social isolation lead to poorer health because they increase inflammation. Inflammation is when your body tells your immune system to produce chemicals to fight off infection or injury. It can also occur when you experience psychological or social stress.
Short-term, local inflammation – such as when you accidentally cut your finger – can be helpful, but having slightly elevated long-term inflammation is associated with poor health. Researchers propose that loneliness and social isolation are linked to this elevated long-term inflammation.