Abstract
According to Michael White, “Light should be interpreted as an architectural material.” Mr. White made his pronouncement at the Annual Conference of the Academy of Neuroscience for Architecture in September 2012, and went on to say that in addition to being economically sound and aesthetically pleasing, the specification of light should address the biology of human health and well being.
Mr. White, an EDAC-certified senior lighting design consultant for the firm Shuler Shook in Minneapolis, Minnesota, was a guest speaker in a panel session titled “Research That Informs Lighting Design in Healthcare Settings.” The other panelists were Sanchin Panda, PhD, a neuroscientist at the Salk Institute for Biological Studies in La Jolla, California, where the conference was being held; Eve Edelstein, PhD, a neuroscientist and associate professor at the University of Arizona College of Architecture, Planning, and Landscape Architecture; and Mark Rea, PhD, a biophysicist and director of the Lighting Research Center at Rensselaer Polytechnic Institute. Like his colleagues, White was concerned with the use of indoor electrical lighting.
People living and working today in the most advanced industrial countries spend the majority of their daylight hours and an average of six hours after nightfall under artificial light. Research has shown that in the absence of full-spectrum sunlight, individuals are susceptible to detrimental effects (Veitch et al., 2008). Conventional candescent and/or “cool white” fluorescent lamps have been implicated in aggravating fatigue, depression, aggression, eye strain, dyslexia, tooth decay, reduced muscle strength, obesity, and diabetes. The lack of exposure to ultraviolet radiation impairs the body's ability to absorb calcium, produce vitamin D3, and stimulate the neuroendocrine system to destroy a wide range of microorganisms that might otherwise lead to hospital-acquired infections (Braun, 2008). In the 1960s, fluorescent lamps were engineered to simulate the natural outdoor environment in both the visible and non-visible UV wavelengths. However, because of legal concerns and the cost of production, this type of fixture never became widely available in the United States.
Sunlight deficiency and the typical measures taken to compensate this deficiency may negatively affect one's sleep/wake cycles, which in turn may cause cardiovascular disorders (Edelstein et al., 2007) and cancer (Stevens et al., 2001). Electrical lighting codes and standards with an emphasis on energy efficiency often require insufficient footcandles during the day and too much light intensity at night for normal circadian function. Nurses and doctors assigned to shift work and patients who are continually exposed to illumination are unable to entrain (or align) with their 24-hour natural rhythms (Schernhammer et al., 2001). Our understanding of sleep disorders was greatly enhanced by the 1998 discovery of melanopsin retinal ganglion cells, a type of photoreceptor in front of the eye's retina that provide signals to the suprachiasmatic nucleus (SCN), the brain's master clock (Hatori et al., 2010). These newfound cells project to many other brain regions as well, influencing countless aspects of human physiology.
There is currently enough evidence to assist designers, architects, and engineers in selecting the proper type and sufficient quantity of light for different healthcare settings. It is critical in preventing errors such as misreading charts and medication labels, or a patient's vital signs. Knowing that a cool color temperature as in blueish white suppresses melatonin in humans and activates the brain means that this type of lighting should not be specified above a hospital patient's bed at night, but that it may benefit those with dementia in long-term care facilities by boosting their activity levels during daytime hours (Holtzman, 2010). Studies have indicated that more light should be layered and diffused to help define the physical properties of an architectural space. Task lighting should be used in combination with ambient fixtures to respond to changes in human activity. Lighting controls should be designed to support these variations. Moreover, personal sensors should be integrated with control algorithms to fill in where the brain has no capacity to guide the individual.
Light-emitting diode (LED) technology is dramatically changing what is possible with electrical lighting. The development of diode lasers is considered a next step in commercial applications, in spite of a limited spectral power distribution (Cao et al., 2006). Fiber optic systems that transfer daylight to remote building interiors are already in use (Muhs, 2000). It was not by chance that representatives of General Electric were in the audience while the conference panel session was being conducted. Like other building product manufacturers, they are part of the value proposition, along with healthcare owners, staff, consultants, and researchers, to continually pursue improvements in the design and construction of environments where a variance in age, gender, and maladies is being served.