Researches made clear the reason alcohol has an effect on human sexuality as described in Shakespeare's Macbeth, "It provokes the desire, but it takes away the performace."

    Reports from Harvard Medical School say that alcohol directly suppresses production of testosterone, a major male sex hormone.

    "When alcohol enters gonadal tissues such as the testicles," the report says, "it is broken down by biochemical processes that ordinarily would be used to make testosterone. The oftnoted paradox in male sexual performance during alcohol intoxication may be associated with decreased levels of testosterone."

    Then comes the next step. When testosterone levels are lowered in blood following heavy alcohol intake, this decrease signals the brain to activate the pituitary gland （often called the master gland） to secrete a hormone （luteinizing hormone） that stimulates testosterone production. It is believed that this process may be associated with increased sexual desire during alcohol intoxication."

    Increased desire, decreased performance – a frustrating scenario for drinkers.

    像在莎士比亞的《麥克白》中描述的那樣，酒精對人們的性欲會產生影響，"它刺激欲望，但它會影響性能",研究人員對此原因作了澄清。

    哈佛醫學院的報告稱酒精直接抑制了睪丸激素的產量，睪丸激素是一種主要的男性荷爾蒙。

    "當酒精進入性腺組織比如睪丸時，"研究中說到，"酒精通過生化過程被分解，分解產物通常會被用來制造睪丸激素。酒精中毒期間男性性行為的矛盾可能與睪丸激素水平的下降有關。"

    然后是下一步。當攝入大量酒精后，血液中睪酮水平下降，下降情況會向大腦發出信號刺激腦垂體（常稱為主腺）分泌荷爾蒙（促黃體荷爾蒙）,該荷爾蒙會刺激睪丸激素的產生。人們相信這種過程與酒精過量時性欲增長有關。

    性欲增長，性能下降--對酒徒而言令人挫敗的情景。