From Wikipedia on 21-Sep-2014
Loneliness is a complex and usually unpleasant emotional response to isolation or lack of companionship. Loneliness typically includes anxious feelings about a lack of connectedness or communality with other beings, both in the present and extending into the future. As such, loneliness can be felt even when surrounded by other people. The causes of loneliness are varied and include social, mental or emotional factors.
Research has shown that loneliness is widely prevalent throughout society among people in marriages, relationships, families and successful careers. It has been a long explored theme in the literature of human beings since classical antiquity. Loneliness has also been described as social pain — a psychological mechanism meant to alert an individual of isolation and motivate him/her to seek social connections.
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Americans seem to report more loneliness than any other country, though this finding may simply be an effect of greater research volume. A 2006 study in the American Sociological Review found that Americans on average had only two close friends in which to confide, which was down from an average of three in 1985. The percentage of people who noted having no such confidant rose from 10% to almost 25%, and an additional 19% said they had only a single confidant, often their spouse, thus raising the risk of serious loneliness if the relationship ended. The modern office environment has been demonstrated to give rise to loneliness. This can be especially prevalent in individuals prone to social isolation who can interpret the business focus of co-workers for a deliberate ignoring of needs.
Whether a correlation exists between Internet usage and loneliness is a subject of controversy, with some findings showing that Internet users are lonelier and others showing that lonely people who use the Internet to keep in touch with loved ones (especially seniors) report less loneliness, but that those trying to make friends online became lonelier. On the other hand, studies in 2002 and 2010 found that “Internet use was found to decrease loneliness and depression significantly, while perceived social support and self-esteem increased significantly”[this quote needs a citation] and that the Internet “has an enabling and empowering role in people’s lives, by increasing their sense of freedom and control, which has a positive impact on well-being or happiness.”
The one apparently unequivocal finding of correlation is that long driving commutes correlate with dramatically higher reported feelings of loneliness (as well as other negative health impacts).