There's been a lot of change in a short period of time when it comes to light bulbs. You may have made the switch to CFLs to cut your energy bills and been disappointed that the bulbs didn't last as long as advertised or that they cast an unflattering light. (Even I'll admit to the eco-sin of putting an incandescent bulb back into my favorite reading lamp because I couldn't stand the fluorescent glow.)

But LEDs have been on the market for a few years now, and prices for them have come way down (about $10-$20 a bulb). The good news is that even though they're still more expensive than CFLs, they really do last much longer (50,000 hours versus 8,000 hours for a CFL versus 1,200 hours for an incandescent) and use significantly less energy (about half the yearly energy cost of CFLs and 1/10 the cost of incandescents). 

So how do you shop for the best bulb for your space? Right now there are several brands — Cree, Sylvania, GE, Lighting Science (sold by Home Depot as their in-house EcoSmart brand) and Philips. Even though they all use the same light rating systems (see more on that below), they do vary on practical application, according to tests. So first-off, make sure the store where you buy your bulbs has a solid return policy, so you can try a few types and then return what doesn't work for you.

Look for two designation numbers on an LED bulb to understand the type of light it will produce:

Color temperature is what is sounds like — this number indicates how warm or cool a light appears. Warm lights are cozier, and more flattering to our skin tones, so they are best for living areas and bedrooms. Cooler lights can be useful in kitchens, basements, or other places where you want a clearer light (though personally, I put warm-tone bulbs in those places too). Contrary to what you might expect, the higher numbers on this scale are cooler, so if you want a warmer glow, look for a lower number (2,700K to 2,900K is similar to an incandescent bulb). 

The color rendering index (CRI) is a second number that is what it sounds like — the higher the number, the more accurately colors will appear under the light. Look for a number of 80 or higher (out of 100). 

The other numbers you will see on bulb packages are lumens (how bright the light is) and watts (how much energy the bulb actually uses to create the number of lumens indicated). Look for a high lumens number if you want a bright light and a low wattage number, which will indicate an efficient bulb. (This can be confusing for those who are used to buying bulbs by wattage — you're just going to have to decouple the watts number from the brightness because, as with LEDs, you can have just 8 watts of energy running a very bright light.) 

Other considerations include bulb shape (look for a floodlight-style bulb for task lighting) and dimming; there are LED bulbs that dim, but make sure you buy a dimmer LED bulb for a dimmer switch (a non-dimmer LED bulb won't work). 

No, LED bulbs don't contain mercury like CFLs do. "LEDs are much safer than fluorescent because they're not likely to release vapors," Oladele Ogunseitan, a professor of social ecology at the University of California, Irvine told the Wall Street Journal. Ogunseitan co-authored a study that found that while LED light bulbs do contain some toxic materials, "if the case [of an LED bulb] cracks, it poses no risk to individuals." (It's similar to the stuff found in a cellphone). 

So remember, when you do break (or finally) use up an LED bulb, treat it like a small electronic item and dispose of accordingly. If in doubt, check Earth911's searchable database for how to do that in your town. 

Related on MNN: 

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

How to find the right LED bulb
LED bulbs have better light quality and last longer than CFL's. Here's how to find the right glow for your space.