Energy Vampirism

Think for a minute about any paranormal ghost investigation show you might have seen in which the batteries have been drained or people have felt light-headed or dizzy (the latter case not being due to the effects of a fear cage, which would explain most occurrences of that phenomenon). According to Michelle Belanger in her book The Ghost Hunter's Survival Guide, "In most cases, the predations of a vampirizing spirit manifest as attachments - tiny little threads of energy that adhere to the surface of a person's aura and trail off to the spirit itself. Think of the attachments as little straws that a spirit (or spirits) have sunk into our energy so they can sip directly from our vitality" (103).
Spirits can be vampires. According to the ghost in the machine theory, we're spirits with bodies. Why am I mentioning this? Spirits of the dead aren't the only ones who have this ability. "Psychic vampirism is a condition wherein a living person has to regularly and actively take in vital human energy in order to maintain their own mental, physical, and psychic wellbeing" (Belanger 113). Chi is the Japanese word for "blood," but it is also the Chinese word for "energy." Therefore, psychic vampires and the vampires we're used to reading about are somewhat similar in nature, even though psychic vampirism is a lot more subtle and they may not even be aware of what they are doing."It is possible for a psychic vampire to become aware of what they are doing, and with awareness comes a choice. A self-aware psychic vampire can learn how to control their natural capacity to take the energy of others and, with practice, they can even learn how to harness their in-born abilities to perceive an manipulate energy to become powerful psychics and healers. Nevertheless, some still choose to be predators, willfully vampirizing the energy of those around them" (Belanger 113).
Ghosts can't eat, so they take energy from electrical devices or the living. In the case of living humans, "a person earns the psychic vampire label if the amount of energy they need to take in is significantly greater than the amount of energy provided through natural means. Chronic illness can often bring this about, but some people are psychic vampires even without a chronic health condition. Their condition may purely be psychic in origin: either they burn energy quicker than their systems can keep up with or, for some reason, they do not get the same sustenance from natural sources" (Belanger 115). It's arguable as to whether blood-sucking vampires need to eat regular food either (in one episode of My Babysitter's a Vampire, Sarah develops a nervous habit of eating bags of junk food so she isn't tempted by a blood drive even though Erica points out they don't need to eat that stuff anymore). Cardcaptor Sakura fans may recall Yue's attachment to Yukito and that as Yue he didn't need to eat whereas Kero didn't need to either but did it for fun anyway. It's not the same thing, but it does come to mind (especially if you include the manga in which Toya gives up his magic so Yukito/Yue wouldn't disappear out of existence, given that life energy and magic are intertwined).
Just as there are vampire slayers, there are psychic energy workers who can remove these attachments for you. In both cases, this may be easier said than done as predators who never say die keep coming back for more - kind of like Myotismon, the vampire Digimon we all love to hate.