Solitude, also known as social withdrawal, is a state of seclusion or isolation, meaning lack of socialisation. Effects can be either positive or negative, depending on the situation. Short-term solitude is often valued as a time when one may work, think, or rest without disturbance. It may be desired for the sake of privacy. Undesirable long-term solitude may stem from soured relationships, loss of loved ones, deliberate choice, infectious disease, mental disorders, neurological disorders such as circadian rhythm sleep disorder, or circumstances of employment or situation.
A distinction has been made between solitude and loneliness. In this sense, these two words refer, respectively, to the joy and the pain of being alone.
Symptoms from complete isolation, called sensory deprivation, may include anxiety, sensory illusions, or distortions of time and perception. However, this is the case when there is no stimulation of the sensory systems at all and not just lack of contact with people. Thus, this can be avoided by having other things to keep one's mind busy.
Long-term solitude is often seen as undesirable, causing loneliness or reclusion resulting from inability to establish relationships. Furthermore, it might lead to clinical depression, although some people do not react to it negatively. Monks regard long-term solitude as a means of spiritual enlightenment. Marooned people have been left in solitude for years without any report of psychological symptoms afterwards. Some psychological conditions (such as schizophrenia and schizoid personality disorder) are strongly linked to a tendency to seek solitude.
Enforced loneliness (solitary confinement) has been a punishment method throughout history. It is often considered a form of torture.
Emotional isolation is a state of isolation where one feels emotionally separated from others despite having a well-functioning social network.
Researchers, including Robert J. Coplan and Julie C. Bowker, have rejected the notion that solitary practices and solitude are inherently dysfunctional and undesirable.