Loneliness is not only emotionally painful; it can harm your health. It’s a risk factor for a host of problems: high blood pressure; sleep problems; decreased ability to deal with the stress of daily life; and the body’s reduced ability to handle inflammation, leading to conditions such as atherosclerosis, rheumatoid arthritis, and tendinitis, as well as a weakened immune system, so you’re more susceptible to illness. Researchers have yet to identify the exact ways these health problems occur, but they know that loneliness seems to make them worse.