A new study, presented last Saturday at the annual meeting of the Society for Personality and Social Psychology, said that people who are lonely experience more reactivation of latent viruses in their systems than people with friends.
Lonely people also are more likely to produce inflammation in response to stress, a factor in heart disease and chronic disorders, reports LiveScience.com.
Lisa Jaremka, of the Institute for Behavioral Medicine Research at Ohio State University College of Medicine, said: "Both, in different ways, indicate that the immune system is a little out of whack."
In the study, the researchers analyzed the blood of the breast cancer survivors for antibodies against cytomegalovirus, a herpes virus. The results revealed that the lonelier the participant, the higher the levels of cytomegalovirus antibodies in the blood.
Jaremka told LiveScience.com: "It's definitely indicating that the immune system is compromised in some way. It's unable at that time, for whatever reason, in this case loneliness perhaps, to keep that virus under control."
Jaremka added that people who are lonely also tend to react more strongly to negative events in their lives. If lonely people experience daily life as more stressful, it may cause chronic stress, which disrupts the immune system.