God said, “Let there be light”—everyone knows that. But God did not specify what color light, and this would eventually prove problematic.
In the age of the LED light bulb, consumers have an unfathomable range of lighting options. This has, perversely, made the task of pleasantly illuminating our homes harder, not easier. The culprit is not LED technology per se, but the bafflingly unhelpful way in which LED bulbs are labeled.
Walk into a well-stocked hardware store, and you will find two main types of bulbs to choose from: “soft white” and “daylight.” (Let’s ignore the existence of Wi-Fi-enabled smart bulbs, which are a solution in search of a problem.) Soft white sounds like it will be the whiter of the two, when in fact it is the more golden option. Daylight sounds like it should be warm and natural; it is instead cold and ugly. The confusing nomenclature has led an untold number of people astray, condemning them to harsh lighting that makes everything in a home, including its residents, less attractive.
For about 99 percent of human history, all artificial light was incandescent, meaning the by-product of heating something to the point that it emits visible radiation. First came fire; then oil lamps, candles, and gaslight; and, finally, Thomas Edison’s incandescent bulb, which operates by heating a filament until it glows. The light produced by an incandescent bulb has a yellow-orange color to it, which we accordingly describe as “warm.” In John Updike’s 1960 novel, Rabbit, Run, Harry Angstrom looks through his neighbors’ windows at dusk and sees, past the pale glow of their black-and-white televisions, “the warm bulbs burning in kitchens, like fires at the backs of caves.”
Incandescent lighting, however, is inefficient: It literally generates more heat than light. This is why budget-conscious institutional settings have long tended to use fluorescent light, which looks awful but uses much less energy. And it is why Congress passed legislation in 2007 mandating the phaseout of incandescent bulbs in favor of LEDs, which use even less. (Donald Trump rolled back that mandate, and then Joe Biden unrolled it; in his second term, Trump is all but assured to un-unroll it.) An LED light works under a wholly different principle from an incandescent one. Instead of heating a filament to the point where light is produced as a by-product, LEDs send electricity through a semiconductor in a way that causes energy to be released as visible photons.
“The first generation of LED lights were just heinous,” Bevil Conway, an artist and a neuroscientist who specializes in color perception, told me. The bulbs emitted a harsh blue-white light by default, creating a terrible first impression for the technology. But the industry has figured out how to “tune” LEDs to generate essentially any color or shade, including something very close to the warm yellow-white of a classic bulb. LEDs still have their share of issues—as I write this, the light in my apartment’s entryway is flickering erratically, as if haunted—but they can glow as warmly as the incandescents of old, while lasting much longer and using much less energy.
If, that is, you can figure out which one to buy.
LED light bulbs are not generally labeled as “warm” or “cool”; that would be too easy. That information is typically buried in the fine print on the side or back of the box. Instead, they have those perplexing labels—remember, “daylight” is cool (despite sounding sunny); “soft white” is warm (despite sounding pale)—and a color temperature, which is measured on the Kelvin scale. You might intuitively think that a higher Kelvin number corresponds to warmer light, but listening to your intuition would be a mistake. In fact, higher-energy light appears cooler. The “soft white” label generally corresponds to 2,700 degrees Kelvin light, while “daylight” is usually applied to 5,000 degrees Kelvin.
What we have here is a classic case of marketing that makes sense to the people selling the product, but not to the people buying it. Indirect natural daylight is, technically, pretty blue. (Perhaps you are familiar with the sky.) When the light-bulb industry labels its 5,000-Kelvin bulbs “daylight,” it’s trying to helpfully indicate that you’re getting a blue light—never mind the fact that a dinky white light bulb does not actually approximate the feeling of sunlight. As for soft white, that “goes back to the incandescent era, where the light emitted from your standard household [bulb] was marketed as ‘soft white light,’” Tasha Campbell, a senior product marketing manager at Signify, which sells Philips-brand light bulbs, told me.
Cold white might have its uses—interrogations, morgues—but the home is not one of them. If you live in an urban area, you can see what I mean by walking around after dark and looking at the windows of an apartment building. If your neighborhood is like mine, most will emit a cozy, warm glow, like fires at the backs of caves. But a troubling share—perhaps one in 10, or one in five—will instead emit a grim, sickly pallor. Those are the daylight apartments.
Bizarrely, some of these apartments are inhabited by people who were not tricked into purchasing terrible lighting, but actively chose it. These are the victims of an extensive body of online propaganda. One popular theory holds that daylight bulbs have a special capacity to help you focus on what you’re doing. “Daylight bulbs are perfect for areas where specific work or detail-oriented tasks are performed,” advises The Spruce, in an example typical of the genre. “These rooms include kitchens, offices, and basements. Bathrooms may also be a good place for daylight bulbs, providing ample light for getting ready.”
The implication is that, until LEDs were invented, everyone was fumbling around in dangerously warm light, unable to chop an onion without losing a finger or read a book without going blind from eye strain. This is preposterous. High-quality cool light can have some advantages for rendering color and detail, which is why it might make sense for, say, an art museum. But if Marcel Proust could write In Search of Lost Time by incandescent lamp, you don’t need 5,000 Kelvins to write an email.
A related theory, popular within the lighting industry, holds that daylight bulbs are “energizing.” A video on the Philips website, for example, says, “Use ‘daylight’ to create a bright, energizing setting for improved concentration.” There’s a kernel of plausibility here. Manuel Spitschan, a professor at the Technical University of Munich who has studied the effects that different-color temperatures have on humans, told me that light suppresses the pineal gland’s production of melatonin, the hormone that tells our brains it’s time to get sleepy, and that blue light suppresses it more than yellow light. The daylight-bulb theory is that cool artificial light will mimic the sun’s “melanomic daylight illuminance” more than warm light will, thus keeping us more alert.
The hitch in this theory is that the pineal gland produces melatonin only when it’s dark out. This means that to the extent that cooler bulbs suppress melatonin, they do so mainly in the time when our bodies are trying to help us get ready for bed, not during business hours. Moreover, Spitschan said that the intensity of light “has a much stronger effect than the color temperature.” When it comes to alertness, very bright beats very white.
Because the world is a big and varied place, I’m willing to believe that some people genuinely prefer a cooler bulb, just as some people presumably prefer Bob Dylan’s most recent albums to his 1960s masterpieces. Good for them, I guess. For everyone else, let there be light—but, for God’s sake, let it be warm.
The post Your Light Bulb Is Lying to You appeared first on The Atlantic.
