Libido refers to a person’s sex drive or desire for sexual activity. The desire for sex is an aspect of a person’s sexuality, but varies enormously from one person to another, and it also varies depending on circumstances at a particular time. Sex drive has usually biological, psychological, and social components. Biologically, levels of hormones such as testosterone are believed to affect sex drive; social factors, such as work and family, also have an impact; as do internal psychological factors, like personality and stress. Sex drive may be affected by medical conditions, medications, lifestyle and relationship issues. A person who has extremely frequent or a suddenly increased sex drive may be experiencing hypersexuality, but there is no measure of what is a healthy level for sex.