There’s a corny old British patriotic song with the words, “Red, white and blue, what does it mean to you?… (Union Jack colors)

If you are like me, you grew up with the “everybody knows” information that red light is challenging, keeps you energized and makes people aggressive; whereas green light is soothing and calming. Remember?

But it’s not true.

It’s like the flat Earth or the belief that heavier-than-air machines could not possibly fly. Wrong!

Recent scientific study has shown that red light is essential for healthy circadian rhythms. Blue light is the problem.

Here’s what Nature does:

1. In the mornings, we awake to yellow light (that delicious golden glow of sunrise!)
2. At mid-day, when we are at our most active, blue light is dominant.
3. In the evening, mellowed reddish colors calm and prepare us for sleep.

Red light encourages the release of melatonin, our “sleep hormone”. Blue light suppresses this vital, healthy rest hormone.

Artificial Light

The trouble is, in our modern world, we are drenched in blue light, 24/7. Fluorescent “white” light is predominantly blue-green. The newer LEDs emit   “white” light that is predominantly blue.

All this has a bad effect on our sleep cycles. It’s dangerous.

See, melatonin is not just the “sleep hormone”, it also protects from cancer, heart disease, obesity and digestive system problems. This shows up in the fact that women shift workers, who stay awake at night and suppress their melatonin, have a measurable increase in breast cancer.

To differentiate night from day, light-sensitive melanopsin receptors in our eyes tune our sleep-wake cycle to match the 24-hour day. These receptors respond to all visible light, but they’re most sensitive to blue, which peaks in natural sunlight at midday.

We are highly sensitive to blue, and although these receptors are in the eyes, they respond even if you can’t actually “see” blue. From midday to dusk, the blue in natural light fades, to be replaced by a reddish tint that stops the suppression of melatonin, reduces our alertness and allows us to get ready for sleep.

But living in artificial light tells our bodies (incorrectly) it’s high noon all the time, when we need to be resting.

Artificial lighting is making us sick. In a 24/7 society saturated in artificial light, our natural systems go adrift. It affects sleep patterns, creates health problems and just generally alters performance and mood in a bad way.

It Affects Animals Too

This affects animals too. Endangered Hawaiian seabirds like the Newell’s shearwater and the dark-rumped petrel were dropping dead in their hundreds. They were getting confused by artificial lighting.

When leaving the nest for their first flight, baby birds are supposed to head towards the bright reflection of light on water. But with street lights shining brightly too, the fledglings get confused. They fly towards the lamps and end up circling them until they drop from exhaustion or collide with buildings.

Baby green sea turtles are also drawn to the artificial light, after hatching on the beach. Heading in the opposite direction from the sea, the turtles become easy prey for predators or get killed as they cross busy roads.

This problem is far worse under the blue glare of LED lamps than under the old-fashioned yellow-orange glow of sodium lamps.

To solve the problem, a light with a unique spectral mix that drastically reduces the blue light content has been developed. The lights have been in production for six years and are now installed in Hawaii, where they lessen the effects of light pollution on animals.

LEDs Can Help

The smart thing to do is get on top of this, as with the animals in Hawaii.

Instead of overriding our body’s response to different colors of light, we can use LEDs to create beneficial variants. The ideal is a tunable white light created from a combination of red, green and blue LEDs. The different hues can be amplified and suppressed over the course of the day to mimic the natural variations in sunlight, thereby keeping our circadian clocks in sync.

NASA is already on to this, since it has a particular interest in its employees’ circadian rhythms. Astronauts, after all, are the ultimate shift workers. They float around in a world where the sun rises and sets every 90 minutes as the International Space Station orbits the Earth. Space offers no margin for error, so they must be at peak performance every moment they are awake. However, the combination of erratic natural light and steady fluorescent light they receive on the space station means that they often struggle to get 6 hours of sleep in 24, never mind the recommended 8 hours [Acta Astronautica, in press].

So they are testing color-tuned LED lighting in lab replicas of the four sleeping compartments on the space station, which enables them to assess what blends and schedules are best for helping astronauts perfect their sleep patterns.

For example, a red-rich mode should help them prepare for sleep as they do personal chores and relax. A yellow-tinged morning light will help them wake. A third setting would provide blue-tinged, alertness-boosting lighting during work periods.

NASA plans for the lights to replace the fluorescent ones now in their sleep quarters in 2015.

If we have the technology to mimic the subtle variations of sunlight, why stop there? We could go one better than nature and create artificial light purpose-built to optimise mood and performance.

Blue light, for example, is bad at night, but at other times it can cheer you up. Indeed, as I was writing in my books 25 years ago, people with seasonal affective depression (SAD) are effectively treated with therapeutic doses of exactly the blue-rich bright light that mimics the midday sun [BMC Psychiatry, vol 11, p 17].

In one recent US military study, soldiers were instructed to do a series of tasks under four different workplace lighting conditions. After a few hours under a dim fluorescent light, their mood was depressed and their performance slipped. Under an LED bulb tuned to mimic the blue hue of midday sun, however, their mood improved significantly and they did better on the tasks [International Journal of Industrial Ergonomics, vol 42, p 12].

And here’s where the red light thing is showing up: bright red light also boosts mood [Lighting Research and Technology, vol 42, p 449].

Some applications could benefit enormously from influencing the mood of their customers, one of them being airlines. Boeing’s new 787 Dreamliner jet is designed for long-haul flights, and in an attempt to provide a more pleasant experience, the company has chosen a special kind of LED light. Instead of the standard white LED, which is actually a blue LED covered with a phosphor layer that converts part of the blue to yellow. It will be using expensive lights that combine red, green and blue light and can be tuned to emit different quantities of each. The cabin will have a “warm reddish” tint, so that people will arrive at their destination feeling more refreshed.

What You Can Do

So far, this fancy adaptable lighting is too expensive for home use. But here’s what you can do:

Have a variety of colored lamps, bulbs and shades. Use photographic gels, if you can’t do it any other way.

• Put on yellow light in the morning.
• Switch to blue during the working day
• Go orange in the late afternoon and warm red for the evenings.

The ultimate smart lighting system is coming: you walk into your house, the sensor system detects who you are and what you need, and adjusts the lights accordingly. Your alarm clock could turn on your bedroom light in yellow wake-up mode in the morning. Night workers, on the other hand, could come home to melatonin-releasing red. We’d all get enough sleep, but you could change the settings if you needed to work late or were throwing a party.

Blue Light Antibiotic

Did you know: blue light can be used to sterilize objects and spaces? I wrote about the value of blue light in my book discussing safe antibiotic alternatives (How To Survive In A World Without Antibiotics). Blue light kills microbes.

It’s logical. Blue light is only slightly longer wavelength than the deadly ultra-violet, which we use extensively for sterilization in our technological society. UV kills everything (including us). Blue light is just that bit gentler… but still useful as a disinfectant.