Eroto-comatose lucidity is a technique of sex magic known best by its formulation by English author and occultist Aleister Crowley in 1912, but which has several variations and is used in a number of ways by different spiritual communities. A common form of the ritual uses repeated sexual stimulation (but not to physical orgasm) to place the individual in a state between full sleep and full wakefulness as well as exhaustion, allowing the practitioner to commune with their god.

The ritual was first documented by Aleister Crowley. However, Crowley may not have been the originator of the rite, and may have learned about it from a female student first.

Crowley wrote in his work De Arte Magica that eroto-comatose lucidity is also called the "sleep of Siloam" and Newcomb notes that this rite preceded Crowley. He points out that Paschal Beverly Randolph ("arguably the single most important figure in the rise of modern sexual magic") called this ritualistic state the "sleep of Sialam." Randolph first discussed the "sleep of Sialam" in his 1873 work Ravalette, but described it at the time as a once-in-a-century prophetic trance. In later writings, Randolph used the term as a more general form of clairvoyant sleep used to understand spiritual things.

Helena Blavatsky may also have taught the technique, calling it the "Sleep of Siloam." In her 1877 work Isis Unveiled, Blavatsky wrote that the trance must be induced through drugs rather than sexual exhaustion. Later, Blavatsky altered her understanding of the rite to mean that drug-induced trance-like state in which a new initiate first comprehends spiritual things. This was described in Blavatsky's 1888 work Secret Doctrine, and she taught that the ritualistic state allowed the individual to either commune with the gods, descend into hell, or perform spiritual acts. Blavatsky taught this was a deep sleep, but Newcomb notes that modern ritualists do not enter sleep but rather a state between sleep and wakefulness.

Sexual practices used for spiritual purposes are not new. Eastern traditions within Taoism and tantrism also incorporated sexual rituals.

Crowley first described the rite in a tract titled Eroto-Comatose Lucidity. The ritual as described by Crowley involves one "ritualist-seer" and several aides. Donald Michael Kraig advises that the more sexually experienced the aides are, the better the ritual works, and that the aides be members of the opposite sex. Religious scholar Hugh Urban, however, concludes that, for Crowley, aides of the same gender as the ritualist (e.g., homosexual activity) was the highest stage of practice of this ritual.

In the first part of the ritual, the aides repeatedly seek to both arouse sexually and exhaust the ritualist. The ritualist is generally passive in this regard. There is disagreement over whether sexual arousal is enough, or sexual orgasm must be eventually accomplished. Crowley and others argue that orgasm must be avoided. Although later practitioners conclude that orgasm does not need to be avoided, that was how Crowley originally formulated the ritual. Most practitioners agree with Crowley that every means of arousal may be used, such as physical stimulation, genital stimulation, psychological stimulation, devices (such as sex toys), or drugs (an entheogen like hashish, marijuana, or other aphrodisiacs). There should be enough aides so that if one aide tires another may take his or her place. Eventually, the ritualist will tend to sink into sleep due to exhaustion.

In the second part of the ritual, the aides seek to come close to awakening the ritualist through sexual stimulation alone. The goal is not to fully awaken them but rather to bring them to the brink of wakefulness. Not all authors agree that the ritualist seer will be in a state between sleep and wakefulness, instead asserting that exhaustion will lead to a trance, or "sleep of lucidity". The ritualist should be neither too tired nor too uncomfortable to aid in the trance-like state.