A psychic vampire is a creature in either human form or phantom-like form that feeds on psychic energy. Some human psychic vampires don't know that they are so they will feed unintentionally on those around them leaving the victim feeling weak with a tired drained feeling.
Night time psychic vampire attacks...
The entity is said to move on top of the victim which gives the victim a feeling of weight on their chests. The pressure on the chest can be felt even if the entity isn't on top of their chest directly so the weight felt isn't from the weight of the entity it's self. Victims have reported seeing the entity surrounded by color. There have also been reports of people hearing voices or a wind tunnel like sound during an attack. The sensations of a night time psychic vampire attack also match up with Astral Walking which is when a person's consciousness detaches from their body.
The daytime attacks are almost always because of a human with the ability and it might not be on purpose. Their victims are usually those around them at the time. The attack will usually leave the victim feeling drained of energy and on extreme cases can cause the victim to pass out for a short period of time. If the psychic vampire doesn't know that they have the ability and doesn't learn to control it then those around them will continue to be attacked. Energy from electronics has also said to be drained around psychic vampires. Everything runs on energy so it is very important for the psychic vampire to learn to control their ability properly.
There is a theory that vampirism of the psychic kind predates popular folklore versions of blood drinking vampires. Some would even go so far as to say that psychic vampirism was the cause of the folklore in the first place. I have also come across some theories that everyone is a psychic vampire in one way or another because we all feed off the energy of each other.
Scientists who have studied psychic vampirism say that the people who engage in vampire behaviors is because of the way they see themselves. In certain situations these vampires behave in ways that make sense to them based on their perceptions, and in turn see no other alternative. Extremists with the ability may seek domination and in some cases even destruction of the victim.
There Are three types of psychic vampirism today.
Type 1: One-on-One Psychic Vampirism
This category includes any form of psychic vampirism between two people with one being the vampire the other the victim.
Type 2: Group Psychic Vampirism
This category also called collective vampirism includes any form of vampirism that involves a group,organization,or institutions.
Type 3: Parasitic Psychic Vampirism
This category is the most different of the three. Parasitic vampirism is an internal form of psychic vampirism turned against the self. This type is the vampire and the victim. Parasitic psychic vampires attack from within so each time they take in energy their bodies ability to cope weakens to minor stress so they feel the need to always feed.
An interview with Joe H. Slate, PH.D. he studies psychic vampirism
An episode about Psychic vampirism from the History Channel
A website with more information about Psychic vampires