Some, but not all, sanguinarians can feed of psychic energy as well. I would check up on some vampire sites like vampires.nu and see what they say.
The truth about vampires and energy:
Many in the vampire community believe that their condition (recently coined as ‘vampirism’ due to the need to feed on human energy) stems from an energy deficiency or the inability to generate enough energy to maintain physical and mental wellness. Many people think that humans couldn’t possibly have an energy deficiency or possibly manipulate energy. Even if the disease DID exist, humans don’t really give off that much energy, right? WRONG!
1. “At rest, the human body gives off nearly 1,600 calories per minute. During active periods, the thermal output jumps to about 2,900 calories per minute [that‘s 4,176,000 calories per day!]. In comparison, the human body gives off about as much heat as a 100 watt light bulb. It's easy to understand, therefore, why a room full of people grows warm just from the accumulating body heat of everyone there. When resting, about 78 percent of the heat is given off by normal heat transfer processes such as conduction, convection, and radiation. 22 percent is given off by the evaporation of perspiration. While working, 45 percent of the heat is lost by normal heat transfer methods and 44 percent through perspiration. The remaining 11 percent goes toward the actual accomplishment of physical work. Calculations based on these numbers indicate that the human being is approximately 11 percent efficient or about as efficient as an internal combustion gasoline engine.”
2. There are several recognized prominent eastern medical practices that involve the natural flow of energy within the human body.
-Qi Gong: The practice of “qi gong” can be translated into English as “the skill of attracting vital energy”. This practice of slow exercises along with concentration of the natural flow of energy has been clinically proven to help “prevent and treat illness, reduce stress, establish balance, integrate mind/body/spirit, bring peace. The teaching of the “skill of attracting vital energy” is not only centralized in the east, but can be found in medical universities in the US such as the University of Wisconsin.
-Acupuncture: This is another eastern medical practice that is becoming more popular among US citizens. Acupuncture is the practice of inserting and manipulating filiform needles into specific points on the human body. The Chinese attribute these points to the flow of qi/energy in the body. But acupuncture is nothing new to the US, it has been around since 1972 when the first legal clinic in a medical school setting in the US, the UCLA National Acupuncture Pain clinic, was established. It has since grown to other major medical institutions such as the Helms Medical institute and even the Harvard Medical School.
-Reiki: This relatively new medical practice was developed by Mikao Usui in 1922. This practice involves the practitioner manipulating the energy/ki within the patient to induce healing of pain or chronic conditions. This manipulation of energies is done by laying hands on the afflicted area and 'feeling' the flow of energy, then either removing it or manipulating it into a healthier flow.
Although the 2008 study of Reiki by M. S. Lee, M. H. Pittler, and E. Ernst came up insufficient, the Harvard Center of Wellness has begun using Reiki on paying clients.
So, if all of these doctors and medical institutions can manipulate energy in the human body, why not “psychic vampires”?