Evidence-based lighting design
Exposure to daylight has long been linked with patient wellness and staff satisfaction, and new research suggests that lighting can improve sleep patterns of elderly patients, reduce medical errors, and even reduce the need for pain medication. These and other studies continue to bring lighting to the forefront of the evidence-based building design process (figure 1).
What can we learn from evidence-based research with regards to lighting? Combining research with lighting strategies delivers better facilities and improved financial performance, even for projects with tight budgets. The result is happier employees and healthier patients.
Evidence at Hand
To promote research-informed design, organizations such as The Center for Health Design (http://www.healthdesign.org) and the Lighting Research Center (http://www.lrc.rpi.edu) are striving to quantify evidence-based research. In line with this, the following studies show how lighting can affect patient health and wellness.
Blue light and sleep patterns. Many older adults experience sleep disturbances because of a disruption of circadian rhythms (biological cycles, including the sleep/wake cycle, that repeat every 24 hours). Physical changes to the eye, neural changes to the brain that affect information processing, and less time spent in sunlight (which helps regulate circadian rhythms) combine to make sleep a challenge for seniors. Elderly patients with Alzheimer's disease are especially prone to sleep disturbances. New research suggests, however, that exposure to blue light can “reduce sleep disturbances and increase the likelihood of stable, consolidated sleep in seniors”.1 The blue light simulates daylight and, at the appropriate color and intensity, can help stimulate the circadian system (table).
For the lobby of Southcentral Foundation in Anchorage, Alaska, a combination of daylight with low-glare indirect light sources reinforces the architecture and provides a connection to the building site.
Sunlight and pain medication. In a recent study, 89 patients undergoing elective cervical and lumbar spinal surgery were assigned to both sunny and shady rooms following their operations. Patients who were exposed to 46% higher intensity sunlight experienced less perceived stress, reported less pain, and took 22% less analgesic medication per hour, resulting in 20% lower pain medication costs.2
Medical errors and light. In a study that evaluated pharmacists’ prescription-dispensing errors, errors were significantly lower at 150 footcandles (2.6%) compared to 45 footcandles (3.8%).3
Effects of day and night on infants. Preterm infants who were exposed to a night/day pattern of light spent more time sleeping, less time eating, gained more weight, spent fewer days on ventilation and phototherapy, and displayed enhanced motor coordination, compared to infants who were exposed to constant light and noise.4, 5 It is important to note that intense light may be a danger to the developing retinas of premature infants; this should be considered in the design of NICUs.
Effect of sunlight on infants. A study of infants who were born before, during, and after awnings were built on a facility's obstetric ward windows over a four-month period revealed that exposure to natural daylight through glass windows may reduce the rate of neonatal jaundice.6
Based on the results of evidence-based research, The Center for Health Design maintains that the vital components of a healing environment are reduced environmental stressors; access to nature; and presence of patient options and choices (control), positive distractions, and social support. Lighting design can significantly reduce environmental stressors by creating a noninstitutional feel, minimizing glare, and enhancing spaces used for relaxation and reflection.
Design of facility spaces. Lighting in clinical spaces should be properly distributed, controllable, and of good color rendition (figure 2). For patient exam rooms, integrating daylight with indirect general illumination creates a soothing effect. Supplemental examination lighting can be fixed or portable, depending on the tasks that are performed in the room.
Red Light (Placebo)
Slept 67% of the time between 12:00 a.m. and 6:00 a.m.
Slept 54% of the time between 12:00 a.m. and 6:00 a.m.
Slept 90% of the time between 12:00 a.m. and 6:00 a.m.
Slept 67% of the time between 12:00 a.m. and 6:00 a.m.
Procedure rooms must have good visibility for staff, but not necessarily high light levels. Providing proper contrast and good color is essential to reducing glare and creating a nonthreatening environment.
Soft ambient light in recovery rooms provides a soothing atmosphere and reduces glare. Multilevel controls permit task lighting for staff and exam lighting for emergencies. The patient should have control of lighting from the bed (typically handled through the nurse-call pillow speaker). Providing access to daylight, views, and a supplemental reading light is also recommended to give patients control of their environment and provide positive distractions.
Glare control. Controlling glare is necessary for both optimum examination visibility and patient comfort. The IESNA Lighting Handbook and the IEEE White Book publish consensus-based standards, including recommendations on room surface reflectances for ceilings, walls, floors, furniture, and equipment. To provide natural daylight without glare, windows should have shades, blinds, or drapes to reduce brightness. The IESNA Lighting Handbook can be purchased through the IESNA Web site at http://www.iesna.org, and the IEEE White Book can be purchased through the IEEE Web site at http://standards.ieee.org.
Indirect lighting in halls and rooms reduces glare, and high color-rendering light sources are provided for diagnostic purposes at Doernbecher Children's Hospital in Portland, Oregon.
Fixture and lamp selection. Many hospitals try to limit the number of fixture types for consistency of style and easy maintenance. This can result in an institutional look and typically does not address multiple visual tasks. Instead, a standard patient room might have wallwashers behind the bed to illuminate the wall and provide reflected light for reading. Recessed downlights and wallwashers produce a residential look and feel. If the ceilings are high enough, indirect lighting with dimming can also provide comfort and efficiency without feeling institutional. While the cost for either option will be somewhat higher than a more utilitarian troffer, the end result will be much more appealing.
In terms of lamps, it is generally best to use one lamp color (color temperature and Color Rendering Index [CRI]) in all spaces to maintain a consistent quality of light. The CRI of all light sources should be in the mid-80s, and color temperature can be either 3,000 or 3,500K. Although these guidelines are not evidence-based, they have been adopted by most hospitals to provide neutral lighting with good color rendering. This helps ensure that skin tones won't be misleadingly altered and provides a soothing environment for patients.
Other design tips. Providing soft, low-glare, and layered lighting in lounges can help provide a positive distraction from the stress of being in a hospital. Simplifying wayfinding throughout the facility, ensuring that hospital corridors are not disorienting, and illuminating artwork is also recommended.
Lighting can enhance wayfinding by creating a visual rhythm in the corridors that reinforces the architecture. This can be accomplished, for example, by lighting selected signage or artwork, or by lighting the space to eliminate shadow patterns that are spaced in a way to conflict with the door spacing and cause confusion.
Studies show that one-time incremental costs of optimal design and construction can be quickly repaid and “virtually recovered after one year,” with significant financial benefits accruing year after year.7 The following are some strategies to help control lighting costs:
Consider installation of higher-quality fixtures, lamps, and ballasts to reduce maintenance, waste, and replacement costs.
Consider lamp/ballast systems that offer extended warranties of up to five years for ballasts and two to three years for lamps. (Normal warranties are one year for lamps and ballasts.)
Work with a lighting designer to develop a cost model. Designers can provide the expertise to select appropriate lighting equipment and determine whether alternate manufacturers provide equivalent products.
As much as possible, use the facility's existing lamp palette to minimize cost and maintenance. Work with the facilities-management department to determine if any fixtures are standard (exit signs, downlights, etc.), and discuss their procurement concerns.
Request line item budgets for lighting from cost estimators and contractors.
Ask the lighting designer to provide a list of reasonable alternative products if value engineering is required.
Effective lighting uses a balance of evidence-based research, equipment that reduces cost and maintenance, time-tested strategies such as daylighting, and a design team committed to creating healthy environments. When these factors come together, everyone benefits from a healthier environment. HD
Denise Fong, IALD, LC, LEED AP, is a principal and Kristen Nichelson is a corporate communications writer for Candela Lighting Design and Consulting based in Seattle. This article is based on Fong's presentation on evidence-based design at LIGHTFAIR INTERNATIONAL 2006 in Las Vegas.
- Lighting Research Center. Researchers use blue light to treat sleep disturbances in the elderly. At: http://www.lrc.rpi.edu, 2005.
- Walsh JM., Rabin BS., Day R., et al. The effect of sunlight on post-operative analgesic medication usage: A prospective study of spinal surgery patients. Psychosomatic Medicine 2005; 67 156-63.
- Buchanan TL., Barker KN., Gibson JT., et al. Illumination and errors in dispensing American Journal of Hospital Pharmacy 1991; 48 2137-45.
- Mann NP., Haddow R., Stokes L., et al. Effect of night and day on preterm infants in a newborn nursery: A randomized trial. British Medical Journal 1986; 293 1265-67.
- Barass P., Comfort K. Ward design and neonatal jaundice in the tropics: Report of an epidemic. British Medical Journal 1985; 291 400-1.
- Miller CI., White R., Whitman TL., et al. The effects of cycled versus non-cycled lighting on growth and development in preterm infants. Infant Behavior Development 1995; 18 87-95.
- Berry LL., Parker D., Coile RC. Jr., et al. Can better buildings improve care and increase your financial returns? Frontiers of Health Service Management 2004 Fall; 21 3-24.