The lighting and health connection

In modern times, much of the human race has undergone a profound shift in its living patterns. Once spending much of our time being active in nature, it is now normal for those in rich countries to remain indoors, often gazing into screens. Despite a climate that often beckons us outdoors, Australians spend about 90% of their lives in various indoor environments.

This lifestyle has been facilitated by electric lighting, a technology that was quickly adopted around the world following the invention of the light bulb by Thomas Edison in 1879. The effects have been far reaching, with a marked drop in the average number of hours that we spend asleep each night down from nine to only seven.

While lighting is not a subject that usually attracts a lot of attention unless it is deficient, it can affect our health and quality of life. A new science known as photobiology studies the effects of all types of light on living organisms, and more discoveries in this field continue to be made.

Compact fluorescent lamps

The incandescent light bulb, whose globe appearance has scarcely changed since the days of Thomas Edison, is rapidly disappearing. In 2007, Australia became the first country to announce a phase-out, largely driven by the issue of energy efficiency, and many others have followed. Incandescents put out about 90% of their energy in the form of heat.

In their place, the shelves are now full of compact fluorescent lamps (CFLs) that work by ultraviolet light exciting a phosphor coating on the inside of a glass tube, causing it to emit a bright glow. CFLs have the advantage of being far more energy efficient, and unlike the older-style fluorescent tubes they run at a high frequency and emit no visible flicker.

Unfortunately, not everybody is happy with these new lamps. People with light sensitivity conditions such as lupus can be affected by the UV radiation, and the British Association of Dermatologists has warned that light wavelengths emitted by CFLs are capable of causing eczema and skin cancer among the light-sensitive. For electrosensitives, who are believed to perhaps number somewhere around 3% of the population, another concern is the radiofrequency radiation given off.

Each type of lighting has its own colour temperature, expressed in units of Kelvin (K.) The CFL temperature preferred by most people has yellow tones and is known as warm white. With a Kelvin rating of 2700-3000K, it is more aesthetically pleasing than many other colour tones and more closely resembles the glow from an incandescent.

On the other hand there is cool white, which at 4500K is disliked by many people for its similarity to unappealing clinical fluorescent light. In Germany, this light source has been banned from public buildings due to its distorted spectral output, which only occupies a limited area of the lighting spectrum.

For people who are keen to avoid CFLs, a further option is the halogen globe, closely resembling the incandescent but offering energy savings of up to 30%. When dealing with this type of halogen, certain safety precautions are needed. The lamps, which are made from quartz, can become hot, and, for higher wattages, flammable materials need to be kept at a safe distance. Fingerprints can create a hot spot on a lamp that may later cause gas leakage or an explosion; they need to be carefully removed and the lamp allowed to dry before use.

Ultra-efficient LED (light emitting diode) lighting technology is quickly evolving while the price is dropping, and as the brightness improves it is becoming suitable for a growing range of applications.

Lighting for work

Experts generally advise that lighting should be tailored to the type of work being carried out. It is a good idea to ensure that the light is sufficiently bright, and to consider the role of task lighting in illuminating work areas. Reading and writing generally require higher levels of light than computer activities.

When working on a computer, a monitor with a light-coloured surround is easier on the eyes than a dark frame, as it minimises contrast. To avoid issues with reflections, the best positioning is side-on to the main source of light.

Circadian rhythms and melatonin

Those who are exposed to bright natural light tend to have a more regular sleep/wake cycle, while people working indoors may find their sleep patterns disturbed. As a consequence, it is healthy to seek regular exposure to daylight as a means of reinforcing the bodys natural 24-hour circadian rhythms.

This process works via photoreceptors in the brain that transmit light to the optic nerve in the form of electrical energy. In response, the pineal gland in the brain regulates concentrations of the neurotransmitter melatonin that governs the circadian cycle.

Lighting is probably one of the primary reasons why nightshift workers are more prone to health issues. Humans are naturally programmed to be awake during the day and to sleep at night, and a nocturnal work pattern reverses the natural order. Melatonin production normally occurs during the night, a process that is stimulated by dark environments. Exposure to strong artificial light in the small hours depletes melatonin, and in women this in turn pushes up oestrogen levels. Such an increase has been proposed as a factor in the higher incidence of late-term miscarriages and stillbirths by pregnant nightshift workers.

With waking hours having increased at the cost of time spent asleep, we are being exposed to artificial light for extra hours during the evening. Even when in bed with the lamp switched off, light does not necessarily go away. Much urban lighting unnecessarily shines in an upward direction despite the fact that only downward-facing light is of any use. This nocturnal light can put circadian rhythms out of sync, and has been linked to certain cancers, including prostate in men and breast cancer in women. One easy solution is to induce an artificial state of darkness by wearing eyeshades.

Fortunately, some progress is also being made in reducing light pollution by upgrading streetlights using designs that do not emit any light above the horizontal. These are significantly more energy efficient, and are mandatory in some parts of Italy.

The full-spectrum light controversy

Light intensity levels are measured in units of lux, and while office lighting has been measured at around 500 lux, direct sunlight is about one hundred times stronger at around 50,000 lux units. In addition to being far weaker, artificial light sources only operate on a certain wavelength band within the visual spectrum.

Seasonal Affective Disorder (SAD) is the name for a depressive condition linked to circadian disruption that is common in darker Northern Hemisphere climates during the winter months. This type of depression can be ameliorated by going outside more often; even when the sky is dull, it is brighter outside than in an artificially lit indoor environment. Another SAD treatment involves exposure to bright light sources such as light therapy boxes.

While most authorities recommend shielding the eyes with sunglasses, Floridas Hippocrates Health Institute encourages people to spend some time exposing their eyes to full-spectrum sunlight.

For anyone who spends excessive periods indoors, there are astounding benefits from exposure to full-spectrum lighting if some companies are to be believed. Their claims include:

Boosting the immune system.

Greater production among factory workers.

Better visual acuity in classrooms.

Treating arthritis, psoriasis, neonatal jaundice and herpes simplex.

Increased milk production in dairies.

However, according to macular degeneration group MD Support, the blue light that represents one component of full-strength daylight is liable to cause retina damage among older people. The macula is the central area of the retina needed for detailed vision, and for people with macular problems the support group believes that prolonged exposure to blue light may increase the chances of developing cataracts.

MD Support takes the view that potential difficulties with full-spectrum light might begin at about 5000K, with noon daylight ranging from 5000 to 6000K. Two possible solutions are to cut back on exposure, or in place of full-spectrum to develop wide-spectrum lighting that does not exceed the 5000K mark.

Sunlight and the importance of vitamin D

Encouraged by fears about the thinning ozone layer and the risk of skin cancer, in the 1990s we were trained to shun sunlight as a threat to our health, further exacerbating the modern tendency towards indoor living. Now the message has been modified, and a recent position paper issued by a range of groups including the Cancer Council encourages a few minutes sun exposure outside the peak UV period in the middle of the day.

The reason for this shift in attitude is an acknowledgement of the role of Vitamin D. While food sources of this nutrient include fish, milk, eggs, beef liver, and cheese, the easiest pathway for absorption by the body is via ultraviolet light hitting unprotected skin. A powerful antioxidant, vitamin D is being confirmed by an increasing numbers of studies as protective against a range of cancers, including colon, breast and ovarian cancer.

As a result, William Grant of the Sunlight, Nutrition and Health Research Center in California concludes that more lives are saved due to modest sun exposure than are lost from skin cancer. According to his reckoning, most cancer deaths in the US are vitamin-sensitive.

It may not be easy with todays rushed schedules, but there is a lot to recommend embracing a more outdoors existence, and spending more hours under natural rather than artificial light.

Resources

MD Support www.mdsupport.org

Sunlight, Nutrition and Health Research Center www.sunarc.org

Martin Oliver is a writer and researcher based in Lismore (Northern NSW).