Evidence-based lighting design

September 1, 2006
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Integrating proven research and design strategies for healthy lighting

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

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