The facts behind the term ‘healthy lighting’
It is a given that hospital efficiency maximizes the revenues from every invested dollar. “Efficiency” relates to every system in the hospital—including lighting—and can be expressed in terms of staff performance and patient outcomes. Moreover, efficiency can be thought of as both small-scale and large-scale.
Small-scale efficiency of the hospital lighting system focuses on equipment and is measured in terms of first cost and operational cost (e.g., maintenance, energy utilization). Large-scale efficiency of hospital lighting relates to the experience of people—patients and staff—who spend most of their time inside the hospital building.
Research has confirmed that lighting has a direct impact on people's health. With appropriate lighting, patients will be safer and more satisfied with their environment and will recover faster, and staff will stay more alert (especially during the night shift), improve performance, reduce errors, and express more satisfaction. Lighting achieves these results by fulfilling more than its obvious requirement—improving visual acuity to enhance performance of tasks. Lighting also interacts with people's circadian and perceptual systems.
It is now well accepted that light photons received by the retina are then transformed into neural signals and travel to the brain's suprachiasmatic nucleus (SCN)—the “master biological clock”—which regulates the 24-hour cycle of hormone production, melatonin level, subjective alertness, body temperature, and sleep/wake cycle1 known as the circadian system. Lighting is a major factor in stimulating and regulating the circadian system. In this way, lighting can define human behavior and human health.2-5 Specific lighting parameters such as quantity, spectrum, spatial distribution, timing, and duration of exposure become of critical importance for the design of healthy lighting and healthy environments.
Right: People intuitively gather in places of repose and relaxation. Simplicity, order, and clarity are all attributes of nature and result in pleasing, nature-like gathering places.
The perceptual aspect of lighting is also critical to creating healthy environments. Perception is the brain's reconstruction or interpretation of the physical environment filtered through people's previous experiences, associations, expectations, ethnicity, culture, and health status.6 Ideally, the built environment should convey a positive message to most people via the perceptual system. This may appear to be a difficult task because of the great variability in perception among people.7 However, the pioneering research of Roger S. Ulrich, PhD, director of the Center for Health Systems and Design at Texas A&M University, confirms that landscape views accelerate patient recovery.8 Also, the latest-built “green buildings” demonstrate that interiors featuring natural light, plentiful lighting, transparency to lighting, softness of forms, and interconnectedness with nature increase workplace satisfaction and increase productivity by as much as 64%.9
Lighting that stimulates the balanced interaction between the visual, circadian, and perceptual systems is the basis of healthy lighting and healthy environments. The best lighting stimulus for the circadian and the perceptual systems is modulated lighting, or lighting that has a timeline.10 That is to say, healthy lighting is a temporal sequence of “natural” lighting effects that are synchronized with the circadian system.11
For example, healthy lighting for patients will increase the morning/evening light intensity ratio, will increase cumulative light intensity when appropriate during the day, and will dim and shift toward the amber/magenta light spectrum throughout the evening hours. Healthy lighting for the night-shift nurses will have different circadian objectives and a different timeline, for obvious reasons.
As an alternative, the technique of using “light showers” might be beneficial. Light showers basically involve designating a space that nurses can occupy for a short break, perhaps for the writing of notes or a brief report. These spaces are lighted with a high intensity of cool light (4,100K or higher), which will suppress the nurses’ melatonin production.
George Brainard, PhD, a professor of medicine at Jefferson Medical College at Thomas Jefferson University in Philadelphia, has researched the optimal light characteristics for stimulating the circadian system and suppressing melatonin production.12 He has found that high levels of melatonin during the night result in slow reactions, reduced alertness, and increased medication errors. Research conducted at the Lighting Research Center, Rensselaer Polytechnic Institute (New York), further supports the finding that exposure for 10 to 15 minutes to a high level of light increases alertness, suppresses nurses’ melatonin production, and can improve their night-shift work performance.5 Light showers would therefore involve the nurses’ intermittent exposure to high-intensity light at key intervals—for example, before the start of the night shift; at about 11 p.m., when most nurses report “slowing down”; and around 3 a.m., when peak melatonin production occurs.
Also, Charles Czeisler, MD, research professor at the Circadian, Neuroendocrine and Sleep Disorders Section of Harvard Medical School, has formulated a set of practical recommendations—for example, adjustment to the night shift should be performed over five to seven consecutive nights of light exposure and incremental shift delay of the circadian system, with bedtime for the nurses being delayed by one to two hours each night.13 Others have confirmed the validity of this approach.14,15
The good news for hospital planners and designers is that new lighting technologies are becoming a commodity and that the implementation of healthy lighting is reasonably priced. Healthy lighting requires more complex lighting controls than those used for conventional lighting applications but, again, these controls are readily available. The healthy lighting system, as I have conceived it, is an integration of light source fixtures (hardware), lighting controls (software), and easily devised perceptual cues. Fixtures can be conventional light sources with healthy accessories, such as color filters and patterns. The fixtures can be new light sources, such as light-emitting diodes (LED) with the red/green/blue (RGB) spectrum, or a combination of single-phosphor and white fluorescent lamps.
The cost for healthy lighting fixtures can run from 20% higher to two or three times the cost of conventional fixtures. It is important, however, to distinguish between first cost and ongoing operational cost, such as for energy use. Once the fixtures are in place, they take turns in lighting the space during the morning, at noon, or in the evening and can create a more energy-efficient system than a conventional lighting system.
Lighting controls can have different levels of complexity. The economy-sized control package provides individual spaces with healthy lighting, at a cost of about $1,000 to 2,000 per space. The more complex, whole-building controls package is scalable and costs about $25,000 for one nursing station and ten patient rooms. (Incremental cost for expansion is much lower.) A caution, however: Insofar as all this affects human health and well-being, there is no room for do-it-yourself trial-and-error here. Healthy lighting systems must be developed by professionals with a solid grounding in the hard facts of research and the soft concepts of design.
I would conclude by acknowledging that healthy lighting is a novel concept that is not easily sold unless customers persuade themselves by having access to the facts, and have a chance to “play” and see the possibilities for themselves. A good starting point might be to peruse the list of selected references at the end of this article, as well as visiting a 3-D interactive model of a healthy lighting application available on my Web site (also listed below). I also have videos available illustrating this concept.
Those involved in employing healthy lighting worldwide are pioneers, and it is my hope that the American healthcare system will join in furthering this movement, to the benefit of all. HD
Milena Simeonova, RA, NCARB, IES, LC, is President of Milena Lighting Design, Troy, New York. Simeonova has master's degrees in both architecture and lighting from Rensselaer Polytechnic Institute, and her firm has a close working relationship with that institution.
- Rea M. Light: Much more than vision. Proceedings of the EPRI/LRO 5th International Light Research Symposium Orlando 2002.
- lewy AJ., Kern HA, Resenthal NE, Wehr TA. Bright artificial light treatment of a manic depressive patient with seasonal mood cycle. Am J Psychiatry 2002; 139 1469-8.
- Badia P., Myers M, et al Bright light effects on body temperature, alertness, EEG and behavior. Physiol Behav 1991; 50 583-8.
- Boyce P., Becstead JW, Eklind NH, et al Lighting the graveyard shift: The influence of a daylight-simulating skylight on the task performance and mood of nightshift workers. Am J Psychiatry 1997; 29 105-34.
- Figueiro MG., Rea MS, Boyce P, et al The effects of bright light on day and night shift nurses’ performance and well-being in the NICU. Neonatal Intens Care 2001; 14 29-8.
- Liljefors A. Seven steps to a developed theoretical base. Proceedings of the CIE 25th Session San Diego 2003.
- Boyce P. Lighting and the perception of spaces and objects In: Human Factors in Lighting New York:Taylor & Francis, Inc. 2003.
- Ulrich RS. View through a window may influence recovery from surgery. Science 1984; 224 420-1.
- Big&Green Gissen D. Toward Sustainable Architecture in the 21st Century. National Building Museum Washington, D.C., 2003.
- Van Den Beld G. What is healthy lighting at the workplace? Proceedings of the CIE 25th Session San Diego, 1995.
- Simeonova M. Let there be healthy lighting! Lighting Design + Application, San Diego 2003; 33 76-9.
- Brainard GC., Hanifin JP, Greeson JM, et al Action spectrum for melatonin regulation in humans: Evidence for a novel circadian photoreceptor. J Neurosci 2001; 21 6405-12.
- Czeisler CA., Moore-Ede MC, Coleman RH. Rotating shift work schedules that disrupt sleep are improved by applying circadian principles. Science 1982; 217 460-3.
- Campbell SS., Dawson D. Enhancement of nighttime alertness and performance with bright ambient light. Physiol Behav 1990; 48 317-20.
- Rimmer DW., Boivin DB, Shanahan TL, et al Dynamic resetting of the human circadian pacemaker by intermittent bright light. Am J Physiol Regul Integr Comp Physiol 2000; 279 R1574-9.