Little ghosts, goblins and princesses are a welcome sight on Halloween night. But beware of the vampire lurking inside your home.

You could be paying for vampire energy—electricity that leaks from your appliances, computers and entertainment systems—if you leave them plugged in, even when they’re turned off.

Any equipment that is plugged into an electrical outlet draws electricity. So if you leave your mobile phone charger plugged in after you’ve removed the phone, or you leave your computer and scanner plugged in after you shut down for the evening, you could be wasting, and paying for, unused energy.

Most people leave electronics plugged in all the time because it’s convenient to be able to turn them on without having to plug them in again and again, and day after day. The worst offenders are remote "wake up" or "sleeping" appliances, like computers, cable boxes, stereos, TVs, video streaming devices, printers and video game consoles.

As long as these electronics are plugged in, they remain in a “ready” state so they don’t have to "wake up" or warm up when you turn them on. This alone can cost you between $165 and $440 each year in wasted electricity, depending on how many devices you have.

Our tip: Invest in a high-quality power strip—one that will sacrifice itself during a power surge rather than letting the surge ruin the appliance. Plug multiple items into the power strip and unplug the strip before bedtime. That’s easier than unplugging and re-plugging lots of appliances.

Our caution: Don’t overload your home’s electrical circuits by plugging too many appliances into a single power strip. And if you live in an older home, consult an electrician about how much of an electrical load your single outlets can handle.