James' World 2

Click the link below the picture

.

Take a flashlight – the one on your phone will do – turn it on and place the pad of your index finger over the bulb. See that red glow? You might think it’s something to do with blood, but you’d be wrong. It’s photons of red light bouncing around inside your finger, looking for somewhere to land.

This simple experiment is a doorway to one of the most profound and surprising biological discoveries of recent years. “Light is a nutrient,” says Bob Fosbury, who was an astrophysicist at the European Southern Observatory before he turned his attention to the biology of light. That’s obviously true for plants, which use light to make carbohydrates. But it turns out it’s also true for animals and fungi, all of which exploit light in a hitherto unappreciated way. All living organisms – including us – are solar-powered.

Sunlight has long been understood to be critical to life on Earth. But the fact that light is also used to oil the wheels of metabolism is only just, er, coming to light. Long wavelengths, which come from red and infrared (IR) light, are particularly beneficial for creating energy, and are readily available from sources including sunlight and incandescent bulbs.

But changes in lighting intended to help save energy have inadvertently deprived us from this crucial supply. The irony is that just as we have discovered the benefit of red light, we are unintentionally starving ourselves of it.

How modern bulbs starved us of red light

The story begins in the early 2000s with the widespread adoption of two now-ubiquitous energy efficiency technologies. The first was the light-emitting diode (LED), which largely replaced energy-guzzling incandescent bulbs. Although this change helped conserve energy, it had other unforeseen consequences. The second was window glass that filters out IR, designed to prevent heat leaking into or out of buildings. Together, these dramatically narrowed the spectrum of light we are exposed to indoors, an environment where most humans spend up to 90 per cent of their time. “We lost about 95 per cent of the spectrum,” says neuroscientist Glen Jeffery at University College London. “Suddenly, without warning, boom, the long wavelengths go. And that’s a problem.”

For the vast majority of human existence, those long wavelengths of light were unavoidable. Daylight is rich in visible red light, which has wavelengths of about 650 to 750 nanometres. It also emits vast and invisible (to us, at least) quantities of IR, which extends out to about 2500 nanometres.

People who spend much of the day outside are naturally exposed to these long wavelengths, even when fully clothed. When long-wavelength light hits a human body, it sails through clothing and penetrates deep into tissues (short-wavelength light such as UV, in contrast, is absorbed by clothing, which is why covering up helps prevent sunburn). Red and IR are also abundant in moonlight and in the glow of a campfire. Indoor light, too, used to be full of these wavelengths, either from sunlight streaming through windows or light sources such as open fires, candles, and oil and gas lamps. The invention of the electric light didn’t change that, as the spectrum of an incandescent light bulb closely matches that of the sun.

But the adoption of energy-efficient lighting and windows robbed us of longer parts of the spectrum. Glass that filters out IR obviously blocks that portion of sunlight, and while LEDs throw out a lot of visible light, they produce nothing beyond about 750 nm. “LEDs are completely dark in the infrared,” says Fosbury. Scott Zimmerman, founder of the lighting company Silas Inc. in New Jersey who collaborates with Fosbury and Jeffery, calls LED light “ultra-processed”, an analogy with ultra-processed food. The combined effect of ultra-processed light and modern glass means that the average human today receives much less long-wavelength light than their ancestors did.

At the same time, conditions such as obesity, type 2 diabetes, dementia and early-onset cancers are on the march. The usual suspects for this are poor diet and lack of exercise. But according to Fosbury, Jeffery and others, these are only a piece of the puzzle; another reason, perhaps the principal one, is red-light deprivation. “There’s not a single cause, but I do increasingly think that light is the most fundamental and dominant one,” says Fosbury. “And it’s probably the easiest one to solve.”

To understand why light is so vital, we have to go back in time again, to the Soviet Union of the late 1980s, where, at the USSR Academy of Sciences in Moscow, a biophysicist called Tiina Karu was experimenting with red and near-infrared light as a therapy. She discovered that they were useful in wound healing and pain management and wondered what the mechanism was. Eventually she hit on energy metabolism, specifically the pace at which mitochondria inside the body’s cells produce a molecule called ATP. Red light, she found, accelerated this process.

Karu’s work never found a wide audience, mainly because she came from the wrong side of the Iron Curtain, according to Jeffery. But she was right, and today red-light therapy is everywhere, used to promote wound healing and treat skin conditions, hair loss, cognitive impairment, chronic pain, osteoarthritis and much more. The evidence of its efficacy is patchy, but growing, according to John Mitrofanis, a neurologist at the University of Grenoble Alpes in France. There is much debate over the correct doses and wavelengths, but researchers are in agreement that its effects are mediated by mitochondria.

The key to this is the electron transport chain, a complex and highly orchestrated metabolic process that takes in energetic electrons and passes them down a chain of proteins, creating ATP in the process. ATP is biology’s principal energy currency, analogous to cash in an economy. When a cell needs energy to perform a task – say, building new proteins – it uses ATP.

When mitochondria are bathed in red or IR light, the electron transport chain runs a little faster and more ATP is produced – a process Fosbury calls “photometabolism”. The exact mechanism by which ATP production is accelerated remains a point of contention, but what’s certain is that diseased cells are often short of ATP, so a boost can make up the deficit. That, says Jeffery, explains why red-light therapy is beneficial.

It also explains why taking away red light can be harmful. Jeffery points out that all life on Earth evolved in an environment rich in red light and IR, but humans now mostly live in one stripped of those wavelengths. The result is more sluggish ATP production. To add insult to injury, we have also flooded our indoor environment with shorter wavelengths in the form of blue light from screens and LEDs. Blue light inhibits ATP production by slowing down the electron transport chain. Lose, lose.

The effects are insidious. Fosbury likens long-wavelength light to a vitamin and calls the effects of deprivation “21st-century scurvy”, a nod to the disease of vitamin C deficiency that killed and sickened tens of thousands of sailors in the 18th century. Like scurvy, it creeps up on you. “It’s something that accumulates over a period of time,” says Jeffery.

.

.

.

Click the link below for the complete article:

.

__________________________________________