Loneliness is a distressing experience that occurs when a person’s social relationships are perceived by that person to be less in quantity, and especially in quality, than desired. The experience of loneliness is highly subjective; an individual can be alone without feeling lonely and can feel lonely even when with other people. Psychologists generally consider loneliness to be a stable trait, meaning that individuals have different set-points for feeling loneliness, and they fluctuate around these set-points depending on the circumstances in their lives. Individuals’ levels of loneliness typically remain more or less constant during adulthood until 75 to 80 years of age, when they increase somewhat. Prolonged loneliness is associated with depression, poor social support, neuroticism, and introversion. Studies have shown that loneliness puts people at risk for physical disease and that it may contribute to a shortened life span.