Here is a partial list of what one company promises sitting under a small panel of red lights will improve: athletic performance and recovery (owing to faster muscle recovery and joint repair), sleep (thanks to increased melatonin production and a “healthy circadian rhythm”), and skin quality (because of reduced inflammation and increased collagen production).
These red lights, in this case made by Joovv, are one of dozens of at-home versions of what’s known as light therapy, or photomedicine, or photobiomodulation, a technology based on the idea that light can change us on a cellular level. This past summer, the journal Frontiers in Medicine published an issue dedicated to photomedicine, and its 12 articles have an overwhelming effect similar to Joovv’s marketing copy, covering dermatological concerns like aging, skin cancer, and psoriasis as well as autoimmune diseases like type 1 diabetes. I like the way a 2016 journal article phrases it with a bad joke that gives away the researcher’s quiet exuberance: After a brief overview of peer-reviewed light-therapy treatments (for arthritis, hearing loss, and chemotherapy side effects), the conclusion states that “after decades confined to the ‘scientific wasteland,’ [photobiomodulation] may be finally emerging into the light of day (pun intended).”
It's pretty amazing what you can do with light these days, with narrow spectrum LEDs that can only produce the light you want.
A revolution is upsetting the lighting business as LED lightbulbs replace energy-hogging incandescent ones. This is good news for consumers and the environment; using less energy reduces the greenhouse gases that contribute to climate change.
But this shift comes with a cost, exemplified by a century-old lightbulb factory in St. Marys, Pa., that is the latest to shut down.
For much of its long history the LEDVANCE facility, 120 miles northeast of Pittsburgh, produced lightbulbs under the Sylvania brand. Now all it produces is scrap metal.
Times change and so do technology. The truth is the modern light-bulb is far more sophisticated then those outdated technologies, and China built the factories to make the inexpensive advanced, highly-efficent switch-mode power supplies and LED panels that make the modern bulbs much more affordable -- rather then the United States. But as technologies advance, it really is a win for most Americans, even if the old technology manufacturers are left behind.
This is a very interesting video about street lighting.
It turns out humans (and most animals) have a lot of trouble seeing yellow light after dark, which means that much of supposed efficiency of high pressure sodium lights is wasted. Colder light colors, like that of the mostly obsolete mercury vapor lights of 1950s and 1960s, and modern LED bulb are better at lighting up a street with less actual light output. As the video notes, is some evidence today they made a mistake in 1970s ripping out mercury vapors lights in favor of the more "higher laboratory light output per watt" high pressure sodium.
LEDs can be made any color you want based on the phosphorous. Cold white is popular because you can use a dimmer light while it appears brighter to human and animal eyes. Warm white is less disruptive to sleep and wildlife, more pleasant to the eye, and with less light pollution (in theory) but it's harder humans to see. One interesting idea proposed in the video would be to have street lights start out at a lower-output cold white color in the early evening, and switch to a higher-output warm white color in the early hours of the morning, when fewer people are in the street but you don't to disrupt sleep as much.
Another interesting idea from the comments in the video would be to use high pressure lamps (or warm white LED bulbs) in residential neighborhoods, while using well aimed cold white LED in commercial areas, on highways, and other "high crash areas" such as city centers where there many pedestrians crossing the streets. Mixing warm white and cold white strategically could work to further warn drivers -- suddenly transitioning from a warm white color to cold white color could warn the driver that they are entering a "high crash area" and to use extra care proceeding through that area.
