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.Sexual desires are often an important factor in the formation and maintenance of intimate relationships in humans.A lack or loss of sexual desire can adversely affect relationships.In the week following ovulation, the testosterone level is the lowest and as a result women will experience less interest in sex.Also, during the week following ovulation, progesterone levels increase, resulting in a woman experiencing difficulty achieving orgasm.
The 13th day is generally the day with the highest testosterone levels.
Problems can arise from disparity of sexual desires between partners, or poor communication between partners of sexual needs and preferences.
It is the instinct energy or force, contained in what Freud called the id, the strictly unconscious structure of the psyche.
However, the levels of testosterone increase at menopause and this may be why some women may experience a contrary effect of an increased libido.
Certain psychological or social factors can reduce the desire for sex.