En español | You've turned off the TV and other appliances for the night, and you're tucked into bed, fast asleep. But the vampires in your household are still awake. Vampire electronics, that is — devices that use power even when they are turned off or inactive. Even scarier, these vampires don't need the cover of night to do their dirty work: They're silently driving up your electric bill 24/7.

See also: Gadgets that will make life easier.

Take something as commonplace as a cellphone charger. As long as it's plugged into a wall outlet, the charger continues to suck a small current — even when your phone isn't connected. Same goes for all the other battery chargers in the house.

Cellphone chargers and other electrical devices can run up your power bill even when not in use. — Photo by Getty Images

Your DVD or Blu-ray player may be on (as in "in use") just a few hours a month, but it's actually using electricity all the time, in a low-power state. If you start looking, you may find vampires all over your entertainment system. Any device that works with a wireless remote control constantly draws a small amount of power, so the receiver will sense a pressed button.

How much money are we talking about here? For the average household, vampire electronics tack on about $100 a year to an electric bill — certainly not inconsequential over time. There's an environmental toll, too, as vampire devices drain more than 100 billion kilowatt hours of annual U.S. energy consumption, valued at about $10 billion.

Pull the plug, or better yet ...

So how do you slay these vampires? For items like battery chargers that aren't in use, the obvious answer is simply to pull the plug out of the wall. A simple multiplug power strip, which you may be using anyway, lets you defang a string of vampires with a single tug. Of course, that does mean stooping down and searching for the wire the next time you need the charger, and stooping and searching aren't all that appealing.

That's why I recommend a simple, inexpensive gizmo from a company called Belkin, the Conserve Power Switch ($6.99). This ingenious device plugs into a standard outlet and adds a simple toggle on-off switch. Instead of pulling the wire you want to disconnect from the wall, you just flip the switch and the juice stops flowing. No reason you can't attach a power strip to the Conserve Power Switch, either, if you have multiple vampire devices to choke off simultaneously.

When unplugging isn't an option

Yanking out a wire or flipping a switch is practical enough when you're dealing with a handy little phone charger, but shutting down your entire computer system or home entertainment setup is clearly more of a project, particularly since the power strip is often stored out of reach. Fortunately, there are alternative ways to manage the problem.

Granted, we are talking about spending more than $6.99 here, but when dealing with sensitive electronics, you should use more than a simple extension cord. A built-in surge protector will clamp down on stray voltage spikes that can damage your equipment if left unprotected. Adding a remote control option to a multi-outlet surge protector adds only a few dollars to the price, which you end up recouping in power savings anyway.

One good general-purpose choice is another Belkin product, the Conserve Switch Surge Protector with Remote ($40). (There are similar products from companies like Smart Strip and Tripp Lite, but I happened to buy three Belkin products.) In addition to surge protection, you get eight outlets and a wireless remote control to manage the system. I find this one particularly useful for my computer system, which has wires and adapters snaking all around the room to one central location. Two of the outlets are always on, allowing you to leave certain equipment, such as your modem and router, available at your whim. The other six outlets are laid out widely enough to accommodate bulky power bricks (strange how rarely that's a design priority) and linked together electrically. One press on the remote control and all the connected vampires — speakers, printer, desk light, etc. — are instantly held at bay.