December 31, 2008 
By Nancy Shute
When all is said and done, the best guarantee of a long and healthy life may be the connections you have with other people. John Cacioppo, a neuroscientist at the University of Chicago and coauthor of a new book, "Loneliness: Human Nature and the Need for Social Connection" (W.W. Norton, $25.95), talked with U.S. News about the latest research on how relationships affect physical health. Edited excerpts:
Q: Why did you choose to study loneliness?
A: We want to understand what importance our social connections have to people's biology. Early in human history, our species' survival required the protection of families and tribes. Isolation meant death. The painful feeling known as loneliness is a prompt to reconnect to others.
Q: You say that social isolation has an impact on health comparable to high blood pressure, obesity, lack of exercise, or smoking. Can you explain?
A: Loneliness shows up in measurements of stress hormones, immune function, and cardiovascular function. Lonely adults consume more alcohol and get less exercise than those who are not lonely. Their diet is higher in fat, their sleep is less efficient, and they report more daytime fatigue. Loneliness also disrupts the regulation of cellular processes deep within the body, predisposing us to premature aging.
Q: You point out that, oddly enough, loneliness also makes us less socially adept. How?
A: Lonely adults have the same social skills as non-lonely adults, but they don't deploy them as appropriately. We think that lonely individuals feel threatened, and because of that feeling of threat, they're not certain they can trust others. When you see something positive happening to others, you're not sure if you're included, so you're aloof, demanding, or critical.
Q: Is the solution to surround ourselves with people?
A: Loneliness isn't necessarily a result of being alone. Think about a bereaved spouse and the college freshman going away from home for the first time. They can be around a lot of people but feel completely isolated. In humans, perceived isolation is so much more important than physical isolation.
Q: How can each of us manage our own feelings of loneliness?
A: In everyday life, play with the idea of trying to get small doses of the positive sensations that come from good social interactions. Just saying to someone, "Isn't it a beautiful day?" or "I loved that book!" can bring a friendly response that makes you feel better.
When it comes to friendships, some people think that in order to be less lonely, everybody has to like them. That's not true. It takes just one, two, or three people. The person who has 4,000 friends on Facebook is not necessarily the least lonely person, especially if he spends all his time maintaining his Facebook page.
Q: I'm glad you brought up Facebook. Can virtual connections give us what we need?
A: As a substitute for physical means of connection, you actually get lonelier. However, if you are disabled and isolated by virtue of the disability and the Internet is permitting you to make connections, then it decreases feelings of isolation.