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.