Lately, I've been thinking about light bulbs. Flipping through a natural products catalog I find, among the buckwheat-hull-filled yoga mats and water-filtration systems, some two-page spread on "full-spectrum" light bulbs. The catalog insists that full-spectrum lighting has "been proven to improve mood and reduce eye stress and strain." I paid a little bit of attention when super energy-efficient compact fluorescents first hit the market in the mid–'80s but never actually started using them. Is it time to change my light-bulb habits?
The lighting section of my local hardware store offers a bewildering array of bulbs: cool-white fluorescents, warm-white fluorescents, compact fluorescents, tiny halogen bulbs, halogen bulbs sized for standard Edison sockets, Miser bulbs, Longlife bulbs, full-spectrum bulbs—not to mention good old-fashioned Soft Whites.
So, how are all these bulbs different? Which one is the most efficient? Do full-spectrum bulbs really prevent cavities? How much of the packaging terminology is bogus marketing hype? Here are answers to these questions, as well as everything else you ever wanted to know about light bulbs (and some you didn't).
There are four things you need to know when you're considering a bulb:
The Main Types of Bulbs
Light bulbs—or "lamps," as they're known in the industry—work in one of two ways. Some heat a thin strip of metal until it glows—the word incandescent means "glowing or white with heat"—and this is how traditional light bulbs work. Others electrically excite a gas, which then causes a phosphorescent coating to glow (like a fluorescent bulb).
The three main types of lamps you're likely to come across are the traditional tungsten incandescent bulbs, halogens, and fluorescents.
This is the original light bulb. It works by running electricity through a thin filament made of tungsten, which glows when it gets hot. This is an inefficient type of bulb—it takes a lot of juice to get that filament hot enough to glow—and the bulb gets dimmer over time, as tungsten evaporates from the hot filament and coats the inside of the bulb with a dark haze. Eventually the filament wears out and breaks, which is what you hear rattling around inside a dead bulb. The light it produces is much yellower than sunlight, something you've noticed if you've ever tried to take color photographs by lamplight.