Adequate and appropriate light exposure is vital to human function[i] and is recognized as a critical component of the sustainable development of buildings[ii].
Conversely, suboptimal light exposure can negatively affect the alertness, neurobehavioral performance and circadian synchronization of occupants.
Furthermore, in healthcare settings where patients may have sleep and mood disturbances due to brain injury or where healthcare providers may operate on chronic nightshift schedules, the appropriate quality of light exposure may be crucial for patient recovery and staff performance.
Thus, developing strategic circadian lighting systems to enhance the patient experience, while simultaneously optimizing the staff’s ability to provide high-quality care has emerged as a priority for healthcare facility designers.
Daylight and circadian lighting systems
One of the core components of creating healing, productive environments involves connecting patients and staff to nature – specifically, focusing on the duration, intensity and spectral quality of light exposure, which are now known to have broad impacts on human physiology, metabolism and behavior[iii].
Considering this, an emerging priority for designers is to find effective ways to keep the human circadian rhythm – the internal process responsible for resetting the body’s internal “clock” every 24 hours – in balance.
One of the most effective ways to accomplish this goal is to design spaces that provide daylight access to connect patients and staff to the natural changes of light intensity and spectral content. Without having to break the bank, designers can provide views and expose patients and staff to appropriate wavelengths of light at the appropriate time of day to minimize the disruption to the circadian rhythms of those in the facility.
Leveraging fenestration designs that provide access to daylight can effectively expose occupants to adequate levels of Melanopic Lux to entrain the body’s internal timing. While entrained sleep-wake cycles may potentially contribute to improved well-being and recovery times, disrupted sleep-wake cycles are associated with adverse health effects including seasonal affective disorder, cognitive and fatigue problems in cases of dementia, chemotherapy and traumatic brain injury, as well as higher rates of chronic disease among shift workers.
Access to high-intensity, blue-enriched daylight operates as a stimulant, improving alertness which may contribute to the performance of caregivers and safety of patients; this results in a higher level of care.
Daylight is only a piece of the circadian rhythm-focused puzzle.
Healthcare facilities are carefully designing the distribution, intensity and spectrum of electric lighting – particularly during night shifts – to avoid circadian disruptions and supplant the benefits that daylight provides. Also, in specific instances, to make up for a lack of available daylight.
For example, electric lighting that delivers a high-intensity, blue-enriched light during the day and transitions to low-intensity, blue-depleted light in the evening reinforces occupant sleep-wake cycles.
However, in some cases it may be appropriate for night shift workers to have bright workspace lighting to improve immediate-term visual perception, alertness and performance. It is not always clear if this short-term benefit to job performance outweighs the potential to suppress melatonin and phase shift the night worker’s circadian clock. It should be considered that dim lighting at night would have longer-term benefits for shift workers to minimize disruptions to circadian timing, but may be detrimental to immediate task performance.
One approach during night shifts is to use dim lighting strategically in rest areas and break rooms with bright task lighting when and where appropriate, resulting in the improved ability to provide high levels of care when working while minimizing long-term circadian disruption.
LED lighting’s prominence
Over the past several years, LED lighting systems have become the preferred solutions for healthcare facilities. While one of the primary drivers for LED technology development has been for more energy-efficient lighting, LED luminaires also offer indirect distribution, dimming, controllability and spectral tuning that greatly enable lighting to be designed for circadian impacts. Recent advancements in LED lighting have made it easier to develop environments that:
- Strategically distribute indirect lighting, balancing the needs of patients and staff
- Establish network control and dimming of luminaires for flexible and adaptive operation
- Provide spectral tuning when appropriate
- Enable staff to adjust lighting demands for future needs
For example, indirect lighting can be critical at night, as it helps patients avoid having direct bright light in their view, which is often directed at the ceiling where bright downlighting usually occurs. Instead, strategic task lighting for doctors and nurses can be used that avoids bright light directed at the patient.
Beyond the benefits to patients and staff, at the organizational level, LED lighting systems with networked controls and multispectral tuning can positively impact operational efficiencies. The timing and intensity of electric lighting are important variables in circadian lighting design. Network- connected LED lighting systems enable software-based control and dimming that can be updated as research recommendations evolve without updating the luminaire.
For added bonus, multispectral LED lighting further optimizes a space’s ability to adapt to changing needs using software updates without needing to renovate the physical infrastructure.
Combined with energy efficiency, long life and low maintenance, LED lighting systems enable the nuances of circadian lighting design.
Additional research required
Characterization of the melanopsin photoreceptor in the human eye and its impacts on health, physiology, metabolism and behavior is only two-to-three decades old[iv],[v] and the research is still rapidly evolving.
Many components of the physical mechanisms between light transduction in the eye and associated biological or behavioral effects are being investigated concurrently with both the recommendations for design applications and the tools for spectrally resolved non-visual lighting simulation. While our understanding of the link between light and health emerges, recommendations for healthcare lighting design require rigorous and judicious evaluation.
That said, the available evidence – various studies over the past several years have highlighted the ways daylighting and electric lighting can increase alertness, improve mood and cognitive performance[vi], reduce fatigue[vii] and improve patient well-being and recovery[viii] – promises a fundamentally new era for lighting design in healthcare combining energy efficiency, patient health, quality care and adaptive facilities operation.
In general, the healthcare industry has continued to shift more broadly toward an Evidence-Based Design model focused on leveraging strategic insights to better inform decision making for optimal patient and staff experiences over the past several years.
As this trend continues, lighting will be a more critical part of this broader conversation.
Editor’s Note: Be sure to check out more lighting trends in MCD’s March/April issue.
[i] Lucas RJ, Pierson SN, Berson DM, Brown TM, Cooper HM, Czeisler CA, Figueiro MG, Gamlin PD, Lockley SW, O’Hagan JB, Price LLA, Provencio I, Skene DJ, Brainard GC. (2014). Measuring and using light in the melanopsin age. Trends in Neurosciences. 37(1), pp 1-9. DOI: https://doi.org/10.1016/j.tins.2013.10.004
[ii] World Health Organization. (2020). Lighting and Daylighting. Retrieved from https://www.who.int/sustainable-development/housing/strategies/lighting/en/
[iii] Vetter C, Phillips AJK, Silva A, Lockley SW, Glickman G. (2019). Light Me Up? Why, When, and How Much Light We Need. Journal of Biological Rhythms. 34(6), pp 573-575. DOI: https://doi.org/10.1177/0748730419892111
[iv] Czeisler CA, Shanahan TL, Klerman EB, Martens H, Brotman DJ, Emens JS, Klein T, Rizzo JG 3rd. (1995) Suppression of melatonin secretion in some blind patients by exposure to bright light. New England Journal of Medicine, 332, pp 6-11.
[v] Zaidi FH, Hull JT, Pierson SN, Wulff K, Aeschbach D, Gooley JJ, Brainard GC, Gregory-Evans K, Rizzo JF 3rd, Czeisler CA, Foster RG, Moseley MJ, Lockley SW. (2007). Short-wavelength light sensitivity of circadian, pupillary, and visual awareness in humans lacking an outer retina. Current Biology, 17, pp.2122-2128.
[vi] Vandewalle G, Schmidt C, Albouy G, Sterpenich V, Darsaud A, Rauchs G, Berken P-Y, Balteau E, Degueldre C, Luxen A, Maquet P, Dijk D-J. (2007). Brain Responses to Violet, Blue, and Green Monochromatic Light Exposures in Humans: Prominent Role off Blue Light and the Brainstem. PLoS One, 2(11), pp e1247. DOI: https://doi.org/10.1371/journal.pone.0001247
[vii] Sinclair KL, Ponsford JL, Taffe J, Lockley SW, Rajaratnam SM. (2014). Randomized controlled trial of light therapy for fatigue following traumatic brain injury. Neurorehabil Neural Repair, 28(4), pp. 303-313. DOI: 10.1177/1545968313508472
[viii] Ritchie HK, Stothard ER, Wright Jr KP. (2015). Entrainment of the Human Circadian Clock to the Light-Dark Cycle and its Impact on Patients in the ICU and Nursing Home Settings. Current Pharmaceutical Design, 21, pp3438-3442.
