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When thinking about hospital lighting, many people will automatically visualize the bright fluorescent lights throughout the building that make it feel sterile and clean. With advancements in technology and knowledge around the impact light can make on physical and emotional health, hospitals are now starting to consider taking a different approach to their lighting efforts.
This article will talk about the current state of hospital lighting and how we see it changing in the future.
The Current State of Hospital Lighting
The light source technologies currently used in hospital lighting applications include incandescent/tungsten halogen, fluorescent, gas discharge lamps (mercury vapor, metal halides), and Light Emitting Diodes (LEDs). In addition, many hospitals use daylighting in a mixed-mode with electric lighting to achieve energy savings and other health benefits from daylighting. Depending on the lighting requirements of the patients and healthcare workers, types of luminaires used in hospitals include surface mounted, recessed, wall-mounted, pendant, emergency lights, exit lights, and step lights.
Lighting is a significant component of the hospital electrical bill. Hospitals invest in more efficient lighting technologies (dimming controls, vacancy sensors, daylight controls, etc.) to minimize the light power density to meet new energy code requirements. Even though fluorescent is still the dominant technology in hospital lighting, the adoption of LED lighting has been continuously growing in the past few years due to higher efficiency, better color rendering performance, higher operational life, lower operational/maintenance costs, and better control functionality.
However, many hospitals around the US still use 15-20 years old lighting installations and identify many shortcomings.
- Insufficient light levels create eye fatigue for both patients and health care workers
- Improper light intensity distribution creates visual discomfort and operational inefficiencies
- Light flicker creates visual discomfort
- Improper brightness contrast and color rendering properties of the lighting system create operational inefficiencies in healthcare workers’ tasks
- Lack of attention to the human-centric lighting
- Higher electricity costs on lighting due to lower operational efficiency
The Impact Lighting Can Make
The most important aspect of hospital lighting is addressing the requirements of different people, such as doctors, nurses, patients, and other healthcare workers. The doctors and nurses perform many achromatic and achromatic tasks daily. For example, doctors and nurses sometimes need to precisely identify the color of a patient's skin and tissues to make accurate judgments on the medical condition. Therefore, selecting appropriate illuminance levels, color temperatures, color rendering properties, and light distribution is critical in making health care workers’ visual task completion easier (1,2).
The light distribution of the fixture is critical in improving the visibility conditions while minimizing distractions to the patients due to unintended light trespass. This can be achieved using several lighting layers rather than very bright overhead lighting. For example, ceiling-mounted luminaires can provide ambient lighting and task lighting/ examination lamps. Under-cabinet lighting can be used to enhance the illumination at the task plane, which helps health workers complete their tasks more efficiently. Further, task lighting helps keep the ambient lighting at a lower intensity, and energy savings can be achieved through reduced energy usage.
Many studies have shown that control over changing lighting intensity/brightness is essential in hospital lighting. Therefore dimmable lighting fixtures can be used to adjust the light level in a given space based on individual preferences and time of the day. Certain lighting technologies can produce noticeable flickers when used with dimming controls. Selecting luminaires with a lower flicker index can improve visual performance while mitigating the discomfort and distraction due to flicker.
Recently, non-visual aspects of lighting have been a hot topic among researchers. The biological rhythms with periodicity, approximately equal to 24 hours, are known as circadian rhythms. The human circadian rhythms are driven by the light/dark pattern created by the natural solar day.
However, most people tend to spend more time indoors often with poor lighting conditions, which can result in misalignment of circadian rhythms with the natural light/dark pattern. Disrupted circadian systems can lead to undesirable effects such as poor work performance, weight gain, and reduced sleep quality in the long term. Further, nurses frequently do night shifts, resulting in disrupted circadian systems.
Five key factors determine the effectiveness of lighting on circadian health. They are light level (amount of light collected by the photoreceptors during the day), spectrum, the timing of the day, duration, and light exposure history (3).
Circadian stimulus (CS) is a metric developed by the Lighting Research Center (LRC) which quantifies the effectiveness of a light source to suppress melatonin which is also known as "sleep hormone." The threshold for circadian response is 0.1, and it saturates around 0.7. It is recommended to have a CS of at least 0.3 one hour in the morning and a low CS value in the evening. A higher CS value in the morning makes our body more awake and active, and a low CS value will improve melatonin preparing the body for a good night's sleep.
Color-tunable lighting systems vary the correlated color temperature (CCT) throughout the day to emulate the solar spectrum delivering appropriate CS value to the human body. A tunable white (LED) lighting system has also been used in NICUs that supplement natural daylight to regulate newborns' circadian rhythm (4). Recently, Underwriters Laboratories (UL) published a circadian design guideline (DG 24480) that provides a six-step process to achieve effective circadian lighting for indoor and outdoor places. (5)
Future
Even though maximizing energy savings in hospitals is a substantial factor, enhancing the experience of patients, guests, and healthcare workers through lighting will be at the forefront of the lighting designers' and architects' minds.
Hospitals will be shifting from an institutional appearance to a more welcoming and pleasing environment. Human-centric lighting schemes and personalized lighting settings will become prevalent in hospitals. Further, the use of lighting controls or integrating lighting into building energy management systems is likely.
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