Lighting's Impact on Human Health Studied

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"New discoveries about lighting and human health--its impact on breast cancer and Alzheimer's, for example--make us predict that the way we light our offices, homes, and factories will be subject to massive change", says John P. Bachner, communications director of the National Lighting Bureau, a not-for-profit information resource funded by private industry, professional societies, trade associations, and agencies of the federal government.

"Up to now, lighting has been designed almost exclusively to support visual needs," he says. "A growing body of research tells us that lighting can do far more than help us see, however. As we learn more, new lighting system components will be created not only to enhance our visual performance, but to help prevent disease as well."

Circadian Rhythms and Light

Many of light's health effects stem from its ability to influence circadian rhythms, which are 24-hour oscillations in neural activity controlled by a "master biological clock" located in the suprachiasmatic nucleus (SCN) of the hypothalamus.

Recently discovered nonvisual photosensitive retinal ganglion cells (RGCs) connect directly from the retina to the SCN, and there influence the secretion of melatonin by the pineal gland. Melatonin acts somewhat as an anti-oxidant "blood cleaner" as its levels build up while we sleep.

Light inhibits melatonin production at night, and research shows that women who work during late shifts are far more susceptible to breast cancer. "The logical conclusion," Bachner says, "is that those who work at night need to use light - and the absence of light - to create a 'virtual normal' light-dark cycle."

Light and Vitamin D

Light is also associated with the production of vitamin D--"the sunshine vitamin"--a hormone that in some forms (D3) is manufactured in the skin, when light strikes it.

Researchers suggest that people are absorbing less vitamin D3, because they have reduced their exposure to sunlight in order to avoid skin cancer.

In a Finnish study, children who received vitamin D supplements from the age of one year had an 80% decreased risk of developing type 1 diabetes.

Other studies show that people who work long hours indoors tend to be vitamin D deficient, and that vitamin D supplements or exposure to more light could significantly reduce the risk of colon and prostate cancer.

Alzheimer's Disease and Light

Light has also been shown to affect Alzheimer's Disease patients, who ordinarily exhibit random patterns of rest and activity. Through the use of light therapy, an experimental group was able to consolidate periods of rest and activity, greatly easing the responsibilities of caregivers. Interestingly, the wavelengths of the lighting used had an impact on results.

Other Conditions

Other studies show that lighting can cure neonatal jaundice, psoriasis and other skin diseases, seasonal affective disorder, and sleep disorders, prevent myopia, and counteract airborne disease transmission. Studies are under way to look into lighting's impact on high blood pressure and heart disease.

"To some extent," Bachner says, "results are likely to show that the lighting needed to help improve our heath requires more energy than is currently allowed by codes, because the codes are based on the energy needed by lighting designed only to support vision. "

Generally speaking, the amount of electric illumination needed to influence health tends to be about ten times that required for vision. We doubt that government regulators would stand in the way of health, however. Imagine being able to work in an environment where the lighting not only helped you get your job done, but also helped enhance both the quality and quantity of life."