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. 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.