Libido

# Overview
Libido in its common usage means sexual desire; however, more technical definitions, such as those found in the work of Carl Jung, are more general, referring to libido as the free creativeor psychicenergy an individual has to put toward personal development or individuation.
Sigmund Freud (the father of modern psychology) popularized the term and defined libido as the instinct energy or force, contained in what Freud called the identification, largely the loss of the consciousness component of the psychology. Freud pointed out that these libidinal drives can conflict with the conventions of civilized behavior. 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.  Excessive use of ego defenses results in neurosis. A primary goal of psychological analysis is to bring the drives of the identitification into consciousness, allowing them to be met directly and thus reducing the patient's reliance on ego defenses.

# Historical Perspective
According to  Swiss psychologist Carl Gustav Jung, the libido is identified as psychic energy. Duality (opposition) that creates the energy (or libido) of the psyche, which Jung asserts expresses itself only through symbols: "It is the energy that manifests itself in the life process and is perceived subjectively as striving and desire." (Ellenberger, 697)
Defined more narrowly, libido also refers to an individual's urge to engage in sexual activity.  In this sense, the antonym of libido is destrudo.

# Libido Impairment
Sometimes sexual desire can be impaired or reduced. Factors of reduced libido can be both psychological and physical. Loss of libido may or may not correlate with infertility.

## 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.
A comprehensive list:
- Depression
- Stress/fatigue
- Childhood sexual abuse/assault/trauma
- Body image issues
- Affair/attraction outside marriage
- Lack of interest/attraction in partner
- Performance anxiety

## Physical Factors
Physical factors that can affect libido are lifestyle factors, medications and, accordingly to studies, the attractiveness and biological fitness of one's partner. 

### Lifestyle
Being very underweight, severely obese, or malnourished can cause a low libido due to disruptions in normal hormonal levels.

### Medications
Reduced libido is also often iatrogenic and can be caused by many medications, such as hormonal contraception, SSRIs and other antidepressants, Oxcarbazepine, Chlordiazepoxide, Atropine 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.  Affected women may seek herbal and hormonal therapies.  Left untreated, women with low testosterone levels will experience loss of libido, relationship stress and loss of bone and muscle and tissue mass throughout their lives.  (Low testosterone may also be behind 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
A study done in Canada suggests that men's libido levels are also sometimes correlated to their partner's monthly cycle. Women's libido is correlated to their menstrual cycle. Many women experience heightened sexual desire in the several days immediately before ovulation.

# Related Chapters
- Cathexis
- Conatus
- Death drive
- Destrudo
- Eros
- Lust
- Mortido
- Sexual attraction
- Self preservation