According to Dr Jacob Liberman, a pioneer in the fields of light, vision and consciousness, lack of sunlight and our use of artificial lighting is contributing to an epidemic of modern health problems. As the most primal energy, which we’ve evolved under for millions of years, light impacts on our physiology and daily life in dramatic ways. Yet its role in our health is less understood and appreciated than exercise.

Tellingly, human eyes — those portals to light, and an outgrowth of the brain — contain about 100 million rod cells and 7 million cone cells (photoreceptors in the retina) to detect particles of light (photons). Testimony to light’s importance for the human body, a rod cell can detect a single photon.

“The body is a living photocell, stimulated and regulated by light entering the eyes,” Liberman says. “Every function of the human body is light dependent.”

Ninety-eight per cent of light infiltrating the body enters via our eyes, yet most of that isn’t for eyesight, says Liberman. Light sparks, or catalyses, our internal biological processes, including metabolism, hormone production and the synthesis of nutrients such as vitamin D, and therefore calcium regulation. “The body is a living photocell, stimulated and regulated by light entering the eyes,” Liberman says. “Every function of the human body is light dependent.”

Light not only switches on our physiology and tells us when to get up, but it boosts our moods and energy. And, as the tool through which we see our universe, light is a teacher that develops consciousness.

An energy pondered by scientists through the ages, light is fundamental to diverse disciplines including solar energy, agriculture, astronomy, communications, the arts, interior design and healthcare. In recognition of the growing importance of photonics, the science and technology of light, 2015 was proclaimed Year of Light by the United Nations.

Light explained

So what is light? According to Liberman, “[That’s] a very big, big question no one has ever been able to answer. Because, first of all light is invisible. It has no form, although it has a charge.” Sunlight, our planet’s major source of light, is “composed of a variety of energies that are transmitted to Earth in the form of electromagnetic waves”, Liberman explains in his book Light: Medicine of the Future.

“Only a small portion of these waves actually reach the Earth’s surface [most are filtered out by the atmosphere] and only about 1 per cent of the total electromagnetic spectrum is thought to be perceived by the eye.” It’s this tiny, visible portion — composed of all the colours of the rainbow — that’s integral to human health.

Importantly, the human relationship with light has altered dramatically within only a few centuries. As author Jane Brox recounts in Brilliant: The Evolution of Artificial Light, “Five hundred years ago, if you could have seen the Earth from above, cities, towns and villages would have appeared nearly as dark as the oak forests.”

Today, most of us work and live indoors well into the night within artificially lit environments. Increasingly disconnected from nature, including the sun, our interaction with the world occurs largely through light-emitting glass screens. This is of particular concern for the current generation of children — the first to be fully shaped since birth by such a world.

Blue light

The primary light that most impacts on us today comes from LEDs (light-emitting diodes) via a computer screen, Liberman says. Since around 2007, LED backlighting has been used to illuminate the screens of digital computer devices like smartphones, tablets, laptops, computers and TV screens, shares Jim Kokkinakis, an optometrist and senior lecturer at the University of NSW’s School of Optometry and Vision Science.

LEDs are more cost- and energy-efficient than the older LCD technology, but are much brighter and emit far more light on the blue spectrum, he says. “Blue light, especially the violet blue, is at the upper end of the visible radiation spectrum. It has also now been called ‘high energy visible light’. It’s one step away from ultraviolet (UV) light — and we all know that excessive exposure to ultraviolet light is harmful.”

Science is discovering that too much blue light at night “can cause problems in terms of the way your body handles insulin, obesity and mood disturbances”.

Like UV, blue-violet light can penetrate deep into the eye — as far as the retina – and can also cause harm. “It is emerging in clinical data that [blue-violet light] has a negative effect on the health of our eyes,” Kokkinakis says. “In accumulated doses, it has been implicated with retinal damage (macular degeneration). The mechanism is still being studied, but it’s thought to disrupt cellular metabolism at the back of the eye.”

Another issue with our frequent exposure to screens is the close range from which we view them. “Light emitted from a handheld smartphone, 40cm from the eye, is potentially 100 to 1000 times brighter than that experienced from a television four metres away,” Kokkinakis says.

It’s a worry when you consider that, according to statistics from social demographer Mark McCrindle, Australian children spend 27 per cent of their waking hours on electronic media. And Kokkinakis, who runs The Eye Practice in Sydney, reports he’s seeing massive problems with computer-induced eye strain and dry eyes in children.

“Staring at digital devices reduces our instinctive blinking rate (the natural lubrication of our eyes) to around 20 per cent of what is normal,” he says. “Once a desktop screen used only at work, the computer screen has been promoted to a mobile device that is with us 24/7. The effect is exponential. Who knows where we will be in another generation of children?”

Insomnia can be another byproduct of screen time. “Blue light suppresses melatonin production in our bodies,” explains Kokkinakis. “It prevents our natural winding-down mechanism from kicking in.” And, while any light can have that effect, blue light does it more effectively.

The dark side of artificial light

Screens aren’t the only sources of blue light; we’re also inadvertently consuming it from the low-wattage LEDs and CFLs (compact fluorescent lamps) lighting our interiors. Most homes today are lit by CFLs and LEDs, according to Efterpi Soropos, a visual designer and the creator of therapeutic interior spaces called Human Rooms. Commercially, the most common lighting is still fluorescent; in retail, LED predominates, she says.

Fluorescent lighting can cause eye strain, insomnia and headaches, Soropos says, and it can also generate bigger problems. In 1982, The Lancet published a study by the London School of Hygiene & Tropical Medicine and the University of Sydney’s Melanoma Clinic, showing women who worked under fluorescent lighting in an office had double the risk of melanoma of those who worked outdoors.

A more recent report from 2008, examining health issues associated with energy-efficient lighting, linked the radio frequency and UV radiation from CFLs to skin cancer and other health problems. The report, by Dr Magda Havas of Trent University in Canada, called on governments to mandate manufacturers to come up with healthier alternatives to CFL and LED lighting as a matter of priority.

According to Liberman, “the healthiest artificial lights we can get are the ones they’re doing their best to get rid of: the incandescents and halogen light sources.” These emit more red and yellow light. More recently, he says, science is discovering that too much blue light at night “can cause problems in terms of the way your bodies handle insulin, obesity and mood disturbances”.

“Sunlight is like the petrol you put in your automobile. The petrol has a certain octane rating; if the octane is too low, the engine will run inefficiently.”

The tendency you may have to overdose on blue light at night — by staying up late, surfing the net and playing online games — doesn’t help. This is when the blue spectrum, which is also naturally present in sunlight and important then to arouse our physiology, has its worst impact, Liberman explains.

The other major problem with artificial light is its variance, imbalance or deficiency compared to the sun’s light. “Any light source that we’re using indoors that is significantly different from sunlight is going to contribute to problems,” Liberman says. “Even the full-spectrum fluorescents are not very healthy. They have different peaks of energy. They give the impression of being white light but the spectrum is very empty in a lot of areas.”

On the other hand, he continues, “Sunlight is like the petrol you put in your automobile. The petrol has a certain octane rating; if the octane is too low, the engine will run inefficiently. Most of the indoor light we use is so different from sunlight that our health begins to suffer.”

“Malillumination” & the sunlight vitamin

What’s the solution to all of this? We need to get outside. Yet, thanks to the hole in the ozone layer, rising skin cancer rates and the Slip, Slop, Slap campaign, many of us fear the sun.

To this, Liberman counters, “Light is the most powerful nutritional source we have. If you don’t have a daily minimum requirement of light, you will suffer from malillumination. It will impact on you on many levels, including your mood and emotional and mental state, but also your physiological state. The same thing happens as when you take an outdoor plant and put it inside your house — it develops with all kinds of problems. Part of the problem is a lack of light; the other problem is the type of light.”

It’s an assertion borne out by research. According to a large-scale study conducted from 2008 to 2010 by the University of Sydney, many of us aren’t getting enough of “the sun vitamin”, with 33 to 58 per cent of Australians over the age of two deficient in vitamin D, a substance unique in the fact that it’s largely synthesised from skin exposure to sunlight.

A 2012 report published by the Journal of Pharmacology and Pharmacotherapeutics reveals that, globally, 50 per cent of people are deficient in vitamin D. The authors state, “[This] is a particularly important public health issue because hypovitaminosis D is an independent risk factor for total mortality in the general population. Emerging research supports the possible role of vitamin D against cancer, heart disease, fractures and falls, autoimmune diseases, influenza, type-2 diabetes and depression.”

Since 1999, numerous studies show shift workers, who are exposed to bright artificial lighting at night, have a greater risk of hormone-dependent cancers such as breast and prostate cancer.

“Vitamin D may be one of the most important vitamins there are,” Liberman says. He believes many of the diseases of modern civilisation relate to lack of light and our indoor culture. Sunlight lowers blood pressure, blood sugar and blood cholesterol, and increases energy, he says. It also has a disinfectant action as well as the ability to kill bacteria and improve skin conditions like psoriasis.

Also linked to insufficient sunlight is a global epidemic of myopia (nearsightedness) in children, particularly affecting urban East Asia. A 2008 study, led by Professor Kathryn Rose and published in Science News, found 29 per cent of Chinese children living in urban Singapore had myopia. In marked contrast, only 3 per cent of a similar sample of Chinese-descent children living in Sydney had myopia. However, they spent an average of 14 hours a week outdoors, compared to the Singapore children’s average of three hours.

Researchers blame the development of myopia on the lower illumination of indoor lighting, an important factor when it comes to performing near work. Natural sunlight is over 100 times more intense than indoor light. The other factor is staring at closer spaces. “A confined environment supports the development of near-sightedness,” Liberman says. “Animal studies prove this, too. [And the] same thing happens to a person in a submarine.”

Hazards of the sun

Isn’t too much sun bad for us? Yes. Well known effects of overdosing on sunlight — particularly the intense UV portion of the spectrum — include skin cancer, sunburn, ageing of the skin, cataracts and other eye damage, and suppression of the immune system.

We do, though, need small doses of the UV light within full spectrum sunlight, Liberman advises. He thinks sunglasses are fine, but not for wearing every day, all day. “The light going through the eye is continually modulating the body — thus you’re impacting your physiology.” There’s also nothing wrong with sunscreen unless you lather your skin in it all the time: “Your production of vitamin D needs the skin to be illuminated by sunlight.” The keys, of course, are moderation and balance.

The healthful dark

As much as natural light is essential for good health, you also need darkness. According to the International Dark Sky Association (IDA), a global organisation campaigning to reduce light pollution, the abundance of artificial light at night (ALAN) glowing from our homes, car headlights, street lighting and cityscapes threatens the planet, adversely disrupting the natural biological processes of animals and plants, as well as humans.

Since 1999, numerous studies show shift workers, who are exposed to bright artificial lighting at night, have a greater risk of hormone-dependent cancers such as breast and prostate cancer. In response to these studies, in 2007 the International Agency for Cancer Research declared shift work a probable human carcinogen.

According to two 2015 journal reviews, along with light’s well-known role in suppressing melatonin and disrupting sleep, constant illumination at night increases cancer risk, accelerates ageing, disrupts growth in the young and negatively impacts on immune function, metabolic processes, diabetes, heart disease, mood disorders and obesity.

It would seem, when it comes to health, it’s time to embrace your true nature as a creature of darkness and light.

Finding a balance

To achieve the right balance of light for you and your children, try the following tips.

Embrace the dark

• Install light-blocking curtains in bedrooms.
• Get all light-emitting devices — digital and electric alarm clocks and TVs — out of the bedroom.
• At night, switch to warm, red-toned, low-wattage lamps or candles and nightlights. (Red spectrum light suppresses melatonin less than other wavelengths.)
• Turn off all unnecessary lighting.
• Rise and go to bed early.

Reduce blue light at night

• Monitor and restrict children’s screen time.
• Avoid all computer screens at least two hours before bed.
• Install a warm filter option (like f.lux) on your smartphone, tablet and computer.
• Purchase blue-blocking glasses for computer work at night.
• Buy a low blue-light computer screen (such as one from BenQ).
• Take your world offline where you can. Encourage children to use print books, old-style games, landlines and so on.
• Install incandescent or halogen globes over fluorescents and LEDs. Use warm-coloured LED over cold-white.

Dose up on sunlight vitamins

• Liberman suggests at least 20–30 minutes of mild sun a day, exposing as much skin as you can. If increasing your exposure, build up a minute each day to allow your skin to adjust and thicken, avoiding sunburn.
• Encourage children to sit outside for activities like eating, homework, studying and playing — outdoor settings are ideal.
• Install as many big windows and skylights in your home as possible.
• Exercise outdoors.