Studies show loneliness has a greater impact on the death rate than do smoking, drinking, eating or exercise.
An article in a national magazine says a nine-year study by UC Berkeley found people without spouses or friends had a death rate more than twice as high as those with social ties.
"The more such ties, the lower the death rate," said team member Leonard Syme.
This finding was true for all ages, sexes and social classes. It appears to have little connection with other factors such as smoking, drinking, sex or social class.