Loneliness refers to a discrepancy between an individual’s preferred and actual social relations. This discrepancy leads to the negative experience of feeling alone and the distress of feeling socially isolated. Feeling alone does not mean being alone and vice versa. An individual’s prior experiences (1), current attributions (2) and overall preference for social contact (3) influence an individual’s perception of the social environment and this influences loneliness.

There are three dimensions of loneliness:

1. Intimate loneliness (i.e. emotional loneliness)
   This refers to the perceived absence of a significant someone (i.e. a person one can rely on for emotional support in times of crises). This form of connection often has a considerable self-other overlap (e.g. best friends).
2. Relational loneliness (i.e. social loneliness)
   This refers to the perceived absence of quality friendships or family connections.
3. Collective loneliness
   This refers to a person’s valued social identities (e.g. group, school, team).

The three dimensions correspond with the intimate space (1), social space (2) and public space (3).

Intimate loneliness corresponds to the inner core (i.e. intimate space). This can include up to five people. It comprises the people one relies on for emotional support during crises. Intimate partners tend to be a primary source of attachment (1), emotional connection (2) and emotional support (3). This indicates that a person’s marital status is an important predictor of intimate loneliness.

Relational loneliness corresponds to the sympathy group (i.e. social space). This can include anywhere between 15 to 50 people. It comprises core social partners whom one sees regularly and from whom one can obtain high-cost instrumental support. The frequency of contact with significant friends or family is the best predictor of relational loneliness. This plays a bigger role in the loneliness of women than that of men. The quality of friendship is more important than the number of friendships.

Collective loneliness corresponds to the active group (i.e. public space). This can include anywhere between 150 to 1500 people. It comprises individuals who can provide information through weak ties as well as low-cost support. This is a social space in which an individual can connect to similar others at a distance in a collective space. The number of voluntary groups one is part of is the best predictor of collective loneliness. This plays a bigger role in the loneliness of men than that of women.

People require the presence of significant others who they can trust and with whom they can plan (1), interact (2) and work together to survive and prosper (3). The physical presence of others in one’s social environment is not a sufficient condition. It is necessary that one feels connected to others. The perception of the friendly or hostile nature of one’s social environment is a characteristic of loneliness.

Loneliness and depression are not the same. Lonely people believe that all would be perfect if they were united with another longed-for person. Loneliness can lead to physical and psychological dysfunctions. It is a risk factor for cognitive decline and the progression of Alzheimer’s disease.

How a person thinks (1), feels (2) and behaves (3) in a situation determines the amount of stress a situation generates. This is called stress generation. A person’s stress generation depends on attachment styles (i.e. working models of self and others). These working models influence social skills and this, in turn, influences loneliness.