Your PVR may be an insomniac.

That is, it may not be able to sleep.

According to a new study by the Natural Resources Defense Council, many set-top boxes (like the ones used to receive satellite or cable television) use almost the same amount of energy whether they're in use or not.

What's more, the study says, some set-top box setups use more electricity than your refrigerator.

NRDC senior scientist Noah Horowitz says that when several set-top boxes were tested, "Hitting the power button did next to nothing. The box continued to consume near-full levels of power, even at two in the morning. All it did was dim the clock."

Though the NRDC's study focused on U.S. set-top boxes, Horowitz says, "many of the boxes and brands that are installed in the U.S. are the same exact devices installed in Canada."

So why do these devices use so much electricity? There are a few reasons. Often, set-top receiver boxes are left powered on all the time. Couple that with the lack of efficient standby modes, and the aggregate power consumption can become costly.

As consumers, we don't often have a lot of choice when it comes to set-top boxes. Many people simply use the box that comes with their cable or satellite subscription. Opting for a greener television receiver isn't a practical option for most.

Ottawa-based green IT consultant Bill St. Arnaud told me that part of the issue here is that television service providers have little interest in making receivers and PVRs more efficient: "There's no incentive for the cable companies or the telephone companies... because they're not paying for the power."

You are.

And it's not just set-top boxes. Most homes are full of devices that draw power even when they're not in use. For instance, usually, when your TV is turned off, it isn't completely powered down. Rather, it's likely in standby mode, using a small amount of electricity. Ditto for wall chargers, which continue to draw energy even when they're not charging a cell phone or video game. This is what some people call "vampire power" - energy consumed by devices even while they're in standby mode.

But for many set-top boxes, the issue goes beyond vampire power, because these boxes don't even have efficient standby modes. Horowitz explains: "Imagine your DVR box that consumes 35 watts when you're watching The Simpsons. It will consume 34 watts when you turn it off."

So what's the solution? The NRDC study suggests improvements in energy efficiency. They say that better-designed set-top boxes could reduce energy use by 30 to 50 percent.

But Bill St. Arnaud says that's not enough. He told me that building smarter, more efficient devices with standby modes would help the problem, but not solve it. He cites the Jevons paradox, which proposes that as efficiency increases, so too does consumption.

"The problem is that we have so many electronic devices in our home," he said. "And even if they're operating extremely efficiently, they still are going to continue to consume more power as we add more and more devices."

St. Arnaud argues for switching to alternative sources of energy. "If you power these devices -- because they only consume microwatts of power -- from a one-foot square solar panel on your roof, you could power them all in standby mode. Then you wouldn't have this huge drain on your electrical bill."

Though your set-top box may be an insomniac, there are measures you can take today to give it a rest. When you can, turn off or unplug your devices when you're not using them. This can be tricky in the case of PVRs, which don't do a good job of recording The Bachelor without power. But if you're planning to be away from home for extended periods this summer, it might be a good time to unplug that cable or satellite box.

Some manufacturers sell so-called "smart power bars" or "smart power strips." These can tell when your TV is turned off, and then turn off your other devices. Again, these can be problematic for the recording functions of most PVRs. They're less of an issue for non-PVR cable or satellite boxes, but depending on your television provider, you could experience delays after you turn your device back on. Horowitz cautions, "The downside is that when you return, you might have to wait a minute to five minutes for [the box] to reboot."

Often, we don't have much choice when it comes to set-top boxes. We tend to use whatever the service provider installs. But where you do have the choices, you can go for lower-consumption devices. And you can let television service providers know if this matters to you, and you can vote with your dollars.

Now if you'll excuse me, I have some lullabies to sing to my networked media streamer.