Freud developed the idea of a series of developmental phases in which the libido fixates on different erogenous zones—first in the oral stage (exemplified by an infant's pleasure in nursing), then in the anal stage (exemplified by a toddler's pleasure in controlling his or her bowels), then in the phallic stage, through a latency stage in which the libido is dormant, to its reemergence at puberty in the genital stage.
Freud pointed out that these libidinal drives can conflict with the conventions of civilised behavior, represented in the psyche by the superego.
According to her, testosterone levels rise gradually from about the 24th day of a woman's menstrual cycle until ovulation on about the 14th day of the next cycle, and during this period the woman's desire for sex increases consistently.
The 13th day is generally the day with the highest testosterone levels.
It is the instinct energy or force, contained in what Freud called the id, the strictly unconscious structure of the psyche.
It is this need to conform to society and control the libido that leads to tension and disturbance in the individual, prompting the use of ego defenses to dissipate the psychic energy of these unmet and mostly unconscious needs into other forms. A primary goal of psychoanalysis is to bring the drives of the id into consciousness, allowing them to be met directly and thus reducing the patient's reliance on ego defenses.
Freud viewed libido as passing through a series of developmental stages within the individual.
Sex drive can also be affected by medical conditions, medications, lifestyle and relationship issues, and age (e.g., puberty).
A person who has extremely frequent or a suddenly increased sex drive may be experiencing hypersexuality, while the opposite condition is hyposexuality.
Sexual desires are often an important factor in the formation and maintenance of intimate relationships in humans.