The idea of succubus and incubus date back as far as medevial and biblical times. The earliest writings date back to Mesopotamia circa 2400 BC. It was believed that a demonic creature called Lilu or Lilitu (female form) would erotically seduce men and women in their dreams. However, the actual title of Succubus (to lie beneath, Latin) and Incubus (to lie on top, Latin) were not applied to these mythical demons until medevial times.
Throughout the 15th century theologians are documented as having discussed this demons in hopes of determining the origins of these disturbing night prowling deviants.
Succubus and Incubus are one in the same. Throughout history it's been believed that the succubus would come at night and would sexually attack men in their sleep retrieving their semen. They would then transform to their incubus form. They would then transfer this sperm to women in their sleep and impregnate them in the hopes of the woman bearing a gifted child called a cambion. Thereby, deceptively spreading there species into humankind. These creatures can allegedly drain energy, blood and life from humans to strengthen itself to continue it's purpose.
The basic description of a succubus or incubus had remained very much the same early on. Described as gargoylike with wings and tails, horns and scaly skin. As time evovled so did its description. In the 18th and 19th centuries it's description evolved into more humanlike imagery. However, some people that have experienced a visit from the creature still describe it in its original animalistic form.
Reports by people sufferring from nightly visits have described the interaction as very physical, painful and extremely real. They can describe the demonic visitor in extreme detail and recall being immobilized as the creature has its way. Upon its release, many victims show physical signs of an encounter and feel victimized and scared.
Succubus are believed to purely mythological and folklore by psychiatrists and occurrences have been treating patients sufferring from these night visits by way of prescribing antipsychotic medications even though many sufferers have shown no signs of mental illness or any physical disabilities. It's believed in the medical community that these attacks are actually vivid and lurid dreams that occur during sleep paralysis. Sleep paralysis is dreaming while your eyes are open but the brain hasn't fully awakened.
Here is one woman's story of her encounter with an Incubus.
The reality of these entities is still heavily debated within the scientific, psychological, paranormal and spiritual communities. If you or someone you know believes they are sufferring from the effects of a succubus/incubus I would reccommend you seek out a certified demonologist or priest.
As always, I encourage discussion and thank you for enjoying my post.