Impact of Light on Health and Welfare

Scientists have known since as early as the 1700's that light affects living things. Franz Halberg is known as the father of chronobiology, the science which explores the effect of light on humans, including physical and mental health. The EBD (evidence based design) movement is using this information to improve lighting design as it relates to human health.

Getting the appropriate amounts of different types of light can have a pronounced effect on our bodies. Melatonin is a hormone which promotes sleep. The amount our bodies produce is affected by the amount of light exposure we have. Too little light can produce adverse conditions such as diminished immune and endocrine function while several studies indicate that too much electric light could increase one's chances for having many different types of cancer. Our natural circadian rhythm, the response to daily patterns of light, is important in order to avoid health problems. Studies also show that different colors of light cause differing biological reactions.

It is important for designers to know how light should be used in built environments in order to create spaces which promote good health for their occupants. An awareness of how a building's orientation relates to the amount of natural light various spaces receive is imperative when addressing its lighting requirements. The variety of lighting types and intensities required for various persons and tasks should always be considered and options given to allow individuals to control how they need for a specific environment to be lit whenever possible. Consideration should be given to way-finding and egress issues. Glare, light's effect on thermal characteristics and the occasional need to allow darkness are all lighting issues which are often ignored.

Health care facilities offer unique issues. The benefit of window views and the natural light that comes with them cannot override a patient's possible need for sleep and darkness during the day. The patient's requirement for darkness to sleep is also a consideration when providing adequate lighting for the individuals providing his or her care during nap time. Health care workers don't always have the luxury of sleeping during the night and working during the day. Compensating for the health risks involved with the abandonment of the natural circadian rhythm is very important. In addition to the risks mentioned in the beginning of this paper, Vitamin D deficiency is also a concern for workers and patients who are unable to get the sunlight they require. Taking advantage of electric lighting which offers as wide a spectrum as possible will help to mimic the benefits of the sun.

Concerns about health care and other workers who do not have traditional schedules are even more worrisome following a study done in Israel which demonstrates that women who live in neighborhoods with more nighttime illumination are at much greater risk for developing breast cancer than those who reside in darker neighborhoods. The theory is that melatonin suppresses the growth of tumors and increased exposure to florescent bulbs suppresses the body's production of melatonin. Other studies which followed women who work at night, such as nurses and flight attendants, collaborated the Israel study. The World Health Organization is so concerned about the situation that it has classified night shift work as a possible carcinogen. This further reinforces the fact that lighting with full spectrum light needs to be developed and that designers should take advantage of light which mimics the sun as much as possible.

Further evidence regarding the influence which light has over our bodies was demonstrated with a study done to determine if and how Daylight Savings Time affected us. It seems our bodies are creatures of habit and do not respond well to change. In the spring after Daylight Savings Time has gone into play, most of the participants in the study found that their peak activity levels were more in tune to Standard Time. The unfortunate result of this is that we are more likely to suffer from a lower quality of sleep during this disruption of our natural circadian rhythm. Restlessness, sleep disruption and shorter amounts of sleep occur. Scientists suspect that this might be at least partially responsible for the higher numbers of suicides and heart attacks during this time frame.

Before reading these articles I was aware of the importance of quality, routine sleep. Treatment for sleep apnea was a very strong demonstration of that fact for me. I was also aware of SAD and try to compensate for the limited lighting during winter months. However, I was unaware of the other significant problems related to improper lighting. Of all of the aspects of interior architecture, lighting is the part where I feel that I need the most guidance and I am looking forward to learning about the tools which are presently available for a lighting designer and how to use them appropriately. It is also exciting to know that new technologies are being developed which will improve lighting function, appearance and demands on the environment.