Low Libido

Sexual desire can be impaired or reduced. It also may be weak or not be present at all, such as in occurrences of asexuality. Factors of reduced libido can be both psychological and physical.

Absence of libido may or may not correlate with infertility or impotence.

Freud viewed libido as passing through a series of developmental stages within the individual. Failure to adequately adapt to the demands of these different stages could result in libidinal energy becoming 'dammed up' or fixated in these stages, producing certain pathological character traits in adulthood.

Thus the psychopathologized individual for Freud was an immature individual, and the goal of psychoanalysis was to bring these fixations to conscious awareness so that the libido energy would be freed up and available for conscious use in some sort of constructive sublimation.

Psychological factors

Reduction in libido can occur from psychological causes such as loss of privacy and/or intimacy, stress, distraction or depression.

It may also derive from the presence of environmental stressors such as prolonged exposure to elevated sound levels or bright light. Other causes include:

depression
stress or fatigue
childhood sexual abuse, assault, trauma, or neglect
body image issues
sexual performance anxiety

Physical factors

Physical factors that can affect libido include: endocrine issues such as hypothyroidism, levels of available testosterone in the bloodstream of both women and men, the effect of certain prescription medications (for example proscar (a.k.a. finasteride) or minoxidil), various lifestyle factors and the attractiveness and biological fitness of one's partner.

Inborn lack of sexual desire, often observed in asexual people, can also be considered a physical factor.

Lifestyle

Being very underweight, severely obese, or malnourished can cause a low libido due to disruptions in normal hormonal levels. There is also evidence to support that specific foods have an effect on libido.

Medications

Reduced libido is also often iatrogenic and can be caused by many medications, such as hormonal contraception, SSRIs and other antidepressants, antipsychotics, opioids and beta blockers.

In some cases iatrogenic impotence or other sexual dysfunction can be permanent, as in PSSD.

Testosterone is one of the hormones controlling libido in human beings.

Emerging research is showing that hormonal contraception methods like "the pill" (which rely on estrogen and progesterone together) are causing low libido in females by elevating levels of Sex hormone binding globulin (SHBG). SHBG binds to sex hormones, including testosterone, rendering them unavailable.

Research is showing that even after ending a hormonal contraceptive method, SHBG levels remain elevated and no reliable data exists to predict when this phenomenon will diminish.

Some question whether "the pill" and other hormonal methods (Depo-Provera, Norplant, etc) have permanently altered gene expression by epigenetic mechanisms.

Left untreated, with low in testosterone levels will experience loss of libido which in turn can often cause relationship stress , and loss of bone and muscle mass throughout their lives. Low testosterone may also be responsible for certain kinds of depression and low energy states.

Conversely, increased androgen steroids (e.g. testosterone) generally have a positive correlation with libido in both sexes.

Menstrual cycle

Women's libido is correlated to their menstrual cycle. Many women experience heightened sexual desire in the several days immediately before ovulation.

Causes of low libido include not getting enough sleep, unresolved conflicts within the relationship, and suboptimal amounts of testosterone in the body.