Once revered as Ra by the Egyptians, and prescribed as a health tonic in the mid 1900s, today many of us fear the sun – thanks to the hole in the ozone layer, global warming, skin cancer and the ‘Slip, Slop, Slap’ campaign.

However, experts such as Dr Jacob Liberman, an international pioneer in the field of light, say we need to balance this caution with moderate, regular sunlight exposure.

“Everything on this earth has evolved for millions of years under the full spectrum of sunlight,” he says. “We all need a minimum requirement of light. It’s the most powerful nutritional source we have.”

Dr Liberman warns chronic “mal-illumination” can create major imbalances in our mental, emotional and physiological health.

A term originally coined by pioneering photobiologist Dr John Ott, mal-illumination is a catchphrase highlighting a silent epidemic of sunlight starvation and its consequences to human health.

“Light impinging the skin is involved in the synthesis and creation of vitamin D,” Dr Liberman explains.

“It’s maybe one of the most important vitamins there are. Most of the diseases of modern civilisation, of being an indoor culture, directly relate to lack of sunlight.”

Like plants, “we’re primed for outdoor life,” he says. “Prior to 1900, over 90 per cent of the population worked outdoors. As of 2000, over 90 per cent of us work indoors.”

We’re trapped in offices, desperate for some sunlight. Photo: Getty

Beyond building healthy bones

Over the past decade or so, vitamin D has been the latest buzz in health, with scientists discovering the ‘sunlight vitamin’ plays a bigger role in our health than previously thought.

Deficiency in vitamin D has been linked to increased risk of fractures, heart disease, high blood pressure, colon, breast and prostate cancer, arthritis, autoimmune diseases, multiple sclerosis, diabetes, depression, schizophrenia, muscle wasting, birth defects, obesity, the flu, macular degeneration and more.

In addition to vitamin D production via the skin, light hits the retina via our eyes, sparking a cascade of chemical messages to our brain, Dr Liberman explains in the book: Light: Medicine of the Future.

As such, light plays a role in regulating hormones like melatonin, insulin, dopamine and serotonin – that determine blood sugar levels, appetite, sleep, immunity, mood and more.

Due largely to our indoor lifestyles, almost 50 per cent of the global population is insufficient in vitamin D.

A 2008-10 study by the University of Sydney found 33 to 58 per cent of Australians were insufficient in vitamin D.

However, it’s probably best to get your intake from sunlight. Studies on supplementation show mixed results suggesting other beneficial factors in sunlight beyond vitamin D.

For example, recent research in the journal Diabetes, found ultraviolet radiation – not vitamin D supplementation – slowed weight gain and signs of metabolic syndrome in mice.

Recent research showed ultraviolet radiation exposure could slow weight gain. Photo: Getty

How much sunlight do we need?

Dr Liberman suggests at least 20 to 30 minutes daily, beginning slowly to allow your skin to adjust, thicken and build a protective layer against burning.

“If possible, allow larger portions of your body to receive the light. That’s where it’s really beneficial.”

Rather than saving your sun fix for the weekend, he recommends indoor workers get smaller daily exposures. Walk or sit outside during breakfast, lunch, or after work.

Depending on the season, time of day and other factors, a five to ten minute exposure of the arms and legs to direct sunlight yields about 3000IU of vitamin D, according to a 2007 article by American endocrinologist Dr Michael Holick, a leader in the field of vitamin D.

Dr Liberman advocates common sense when it comes to sun exposure, especially in conditions with an excess of sunlight such as northern Australia.

“There’s nothing wrong with wearing sunscreen, sunglasses, sun hats.”

Along with sunburn and skin cancer, too much sun can cause ageing of the skin and cataracts.

“Moderation is the key,” he concludes.

Even just 20 minutes in the sun on your lunch break can have an impact. Photo: Getty

Are you at risk of mal-illumination? 

You’re more likely to be get insufficient sunlight and vitamin D if you fit into any of the following:

• Indoor worker
• shift worker
• Housebound (eg you are a carer or suffer from a disability that keeps you inside).
• Wear thickly applied sunscreen every time you go outside (sunscreen can reduce absorption of UVB by up to 95 per cent).
• You live in a dense or smog-affected cityscape where building or pollution blocks sunlight.
• Dark skinned (darker skin contains more of the pigment melanin which reduces the penetration of UVB).
• Elderly (vitamin D synthesis via the skin reduces as we age).
• Live in residential care.
• Cover your body for personal, religious, medical or cultural reasons.
• Avoid the outdoors, eg spend your leisure time in front of computers and TV screens.
• You live or holiday in a high-latitude country or if, in winter, the hours of sunlight reduce through the season.