Lighting for Improving Sleep in Myeloma Transplant Patients

By:

Mariana G. Figueiro, PhD, Professor and Director, Light and Health Research Center

Allison Thayer, MS, Associate Researcher II, Light and Health Research Center

Our previous column discussed the value of administering circadian-effective light to maintain synchrony of circadian rhythms in multiple myeloma patients who are undergoing transplant in the hospital. To briefly recap, patients with multiple myeloma—a cancer that forms in plasma cells and accumulates in bone marrow, crowding out healthy blood cells that fight infection—spend 2–3 weeks in hospital rooms while undergoing autologous stem cell transplantation to combat the disease. The healthcare environment’s typically low daytime light levels and frequent exposures to light at night can lead to circadian system disruption, disturbing patients’ circadian melatonin rhythm and sleep cycle, thereby compromising their prognosis, recovery, and perhaps even their survival.

We described the results of a study (1) showing that a robust, appropriately timed pattern of light and dark in hospital rooms can promote patients’ circadian entrainment and improve their sleep. This column drills down on how healthcare lighting designers, architects, and facilities managers might go about implementing their own lighting strategies for improving patient outcomes.

Implementation Tips

Whether their hospital stay is two days or two months, room lighting can positively influence patients’ physiological and psychological recovery by improving their sleep during hospitalization. Patient diagnosis, treatment, and comfort require lighting that provides good visibility (following ANSI/IES RP-29-20 guidelines (2)), low discomfort glare (annoyance or pain induced by overly bright sources), and low disability glare (reduction in visibility caused by intense light sources in the field of view). Reflecting a growing concern about low daytime light levels and exposures to light at night typical of healthcare environments, it has become apparent that lighting for patient rooms should also be designed to promote temporal alignment of the circadian system by providing high levels of circadian stimulus (CS) (3-5) through the day and low levels of CS in the evening. Research has demonstrated that circadian-effective lighting regimes can increase sleep time, improve sleep quality, and relieve depressive symptoms in various populations. (6-10)

At a minimum, lighting systems should deliver bright daytime light and dim evening light, ideally (but not necessarily) mimicking the solar cycle’s daily pattern of light and dark. Underwriters Laboratories (UL) Design Guideline (DG) 24480 (11) recommends a six-step process for designing, specifying, and implementing circadian-effective lighting systems to promote circadian alignment and better health.

Step 1: Establish a circadian-effective lighting design criterion (e.g., CS = 0.30).

Step 2: Select a luminaire type (e.g., direct/indirect).

Step 3: Select a light source (e.g., 3000 K LED).

Step 4: Perform photometrically realistic software (e.g., AGi32) calculations for the building space.

Step 5: Calculate CS from the vertical illuminance at the eye (EV) and the light source’s spectral power distribution (SPD).

Step 6: Determine whether the lighting system meets the circadian-effective lighting design criterion; repeat steps 2 – 6 if necessary.

Design Considerations

Patient Position: A primary consideration is to determine which portions of a space are frequented by patients and caregivers, how they use that space, and when they are there. Because hospital beds can be angled to positions ranging from fully upright (patients viewing the walls and windows) to fully reclined (patients viewing the ceiling), room lighting should accommodate both patient orientations without causing glare when viewed directly. To ensure that appropriate CS exposures are being delivered to the patients, vertical illuminance (EV) levels should be measured at the eyes in at least two orientations (Figure 1).

Figure 1. Light measurements at patients’ eyes in hospital rooms should be taken at a minimum of two orientations (45 degrees and horizontal) to accommodate the tilt of patient beds.

Luminaire Selection: The intensity distribution, whether from single or multiple luminaires, will influence how much of the light reaches the patients’ eyes (for circadian stimulation) and the workplane (for caregiver examinations and treatment). Choose luminaires that provide the best horizontal illuminance (EH) ratio. Jarboe et al. (12) compared the efficacy of different distribution types (direct–indirect, direct, and indirect) by consulting various manufacturers' IES photometric data files, ultimately determining that a direct–indirect optic provides the best ratio of EV at the eye to EH on the workplane. Direct-indirect luminaires are generally superior, but keep in mind that differences can occur even within this type. Note, however, that these relationships will change depending on the design criteria and the space being illuminated. Surfaces should be painted a light color to allow for the light to bounce off surfaces and provide diffuse illuminations in the space.

Glare caused by electric lighting, daylight, reflective surfaces, and direct views of light sources can be avoided by selecting the appropriate luminaires and making interior design changes within the space. Indirect luminaires can be used to avoid glare while still meeting visual and circadian system needs, but they may require more energy to accomplish those goals. In addition, glare can be reduced or eliminated by reducing the direct view of the source, selecting non-reflective finishes for surfaces, altering window locations if possible, and/or using window blinds in settings where direct sunlight (as distinct from daylight) can enter the space and cause discomfort.

Photometric Calculation and Modeling: Building upon the fundamentals of occupant and lighting system characteristics, the design can be extended to include information about the room using commercially available lighting design software and either the manufacturer’s published photometric data files (IES, or *.ies) or one’s own user-collected data. This step is invaluable, as it permits simulations of luminaire performance, CS delivery, lighting power density (LPD), and energy usage.

Once you have decided what type of luminaires you will be using, contact the manufacturer to request the lamp’s spectral power distribution (SPD), which represents the radiant power emitted by any light source as a function of wavelength. You will need the SPD to calculate CS. Higher short-wavelength content generally delivers greater CS values for the same amount of photopic vertical illuminance at the eye (EV). But, when it comes to white light sources, the impact of SPD on the delivered CS is low compared to other factors such as EV levels and the luminaire’s intensity distribution. For example, we found that an SPD emitting greater short-wavelength light (CCT of 6000 K) was needed to reach a target CS of 0.3 when the photopic horizontal illuminance (EH) level was set at 300 lx. When the EH level was set at 400 lx, on the other hand, an SPD emitting less short wavelength (CCT of 4500 K) light was needed to reach the same CS.

Temporal Characteristics: As with the lighting system’s configuration and output, the timing and duration of patients’ light exposures plays an important role in their circadian system’s responses. The lighting pattern recommended by the LHRC for patients throughout the day begins with a CS of 0.3 in the morning (7–10 AM) for at least 3 hours, transitions down to a CS of 0.2 for the late morning through mid-afternoon (11 AM to 4 PM), and once again transitions down to a CS of 0.1 for the late afternoon and evening until bedtime (5–10 PM). After bedtime, room lighting should be turned off, and nightlights should be used to permit safe navigation. This schedule can be accomplished using lighting designs employing either static- or tunable-CCT systems.

Figure 2. Simulations of hospital room delivering a high CS of 0.3 in the morning (7–10 AM, left), a medium CS of 0.2 in the late morning through afternoon (11 AM to 4 PM, middle), and a low CS of 0.1 in the late afternoon through evening (5–10 PM, right). Transitions in CS levels are achieved in one hour (lower row of clocks). The lighting is turned off after bedtime. Deviations from this proposed schedule can be made to accommodate the user, as long as the general principle remains — promote the regular use of bright days and dark nights.

Takeaway

Above all, it is important to avoid viewing the design process as a hard-and-fast series of steps that inevitably lead to the desired outcome. Successful designs instead grow from a dynamic interchange between architects, lighting designers, and manufacturers, all of whom fit together as important pieces of a puzzle that might require multiple attempts to achieve an optimal CS performance solution. While we are still learning about the benefits of lighting design for the circadian system, research from our lab and others clearly demonstrates health benefits of creating a robust light–dark pattern to stimulate the circadian system, promote daytime alertness, and avoid disturbances from exposures to the wrong kinds of light at the wrong times of day or night.

References

1. Valdimarsdottir HB, Figueiro MG, Holden W, Lutgendorf S, Wu LM, Ancoli‐Israel S, et al. Programmed environmental illumination during autologous stem cell transplantation hospitalization for the treatment of multiple myeloma reduces severity of depression: A preliminary randomized controlled trial. Cancer Medicine. 2018; 7: 4345-4353.

2. Illuminating Engineering Society. Lighting for Hospital and Healthcare Facilities. ANSI/IES RP-29-20. New York: Illuminating Engineering Society, 2020.

3. Rea MS, Figueiro MG, Bullough JD, Bierman A. A model of phototransduction by the human circadian system. Brain Research Reviews. 2005; 50: 213-228.

4. Rea MS, Nagare R, Figueiro MG. Modeling circadian phototransduction: Retinal neurophysiology and neuroanatomy. Frontiers in Neuroscience. 2021; 14: 1467.

5. Rea MS, Nagare R, Figueiro MG. Modeling circadian phototransduction: Quantitative predictions of psychophysical data. Frontiers in Neuroscience. 2021; 15: 44.

6. Figueiro MG, Hunter CM, Higgins PA, Hornick TR, Jones GE, Plitnick B, et al. Tailored lighting intervention for persons with dementia and caregivers living at home. Sleep Health. 2015; 1: 322-330.

7. Figueiro MG, Plitnick B, Roohan C, Sahin L, Kalsher M, Rea MS. Effects of a tailored lighting intervention on sleep quality, rest–activity, mood, and behavior in older adults with Alzheimer’s disease and related dementias: A randomized clinical trial. Journal of Clinical Sleep Medicine. 2019; 15: 1757-1767.

8. Figueiro MG, Kalsher M, Steverson BC, Heerwagen J, Kampschroer K, Rea MS. Circadian-effective light and its impact on alertness in office workers. Lighting Research & Technology. 2019; 51: 171-183.

9. Figueiro MG, Sahin L, Kalsher M, Plitnick B, Rea MS. Long-term, all-day exposure to circadian-effective light improves sleep, mood, and behavior in persons with dementia. Journal of Alzheimer's Disease Reports. 2020; 4: 297-312.

10. Figueiro M, Kales H. Lighting and Alzheimer’s disease and related dementias: Spotlight on sleep and depression. Lighting Research & Technology. 2021; 53: 405-422.

11. Underwriters Laboratories. Design Guideline for Promoting Circadian Entrainment with Light for Day-Active People, Design Guideline 24480, Edition 1. Report # DG 24480. Northbrook, IL: Underwriters Laboratories, 2019.

12. Jarboe C, Snyder J, Figueiro MG. The effectiveness of light-emitting diode lighting for providing circadian stimulus in office spaces while minimizing energy use. Lighting Research & Technology. 2019; 52: 167-188.