Be Creative! Three Approaches to a Tailored Lighting Intervention for Improving Sleep-Wake Cycles in Dementia Patients

By MARIANA G. FIGUEIRO AND DAVID PEDLER

Light and Health Research Center at Mount Sinai

In previous Light and Health Research Center (LHRC) contributions to designing lighting (dl), we described studies employing tailored lighting interventions using circadian stimulus (CS) to improve sleep using single devices among nursing home residents living with ADRD and home-dwelling patients living with a related neurodegenerative disorder, Parkinson’s disease (PD). Those studies showed that, despite the difficulties commonly encountered when delivering therapeutic lighting interventions in the field, the simple principle of promoting brighter days (i.e., high CS), dimmer evenings (i.e., low CS), and darker nights can significantly improve objectively and subjectively assessed sleep outcomes. Because patient compliance can pose formidable challenges to the efficacious application of nonpharmacological light therapies in controlled settings, the key to success in field studies lies in being able to deliver the treatment as participants go about their daily activities.

This study followed the same general approach described in our previous two articles but differed in its use of three separate lighting systems/devices among 14 cognitively impaired participants with sleep disturbances residing in three separate assisted living and memory care facilities in Westborough (5 participants), Northborough (4 participants), and Medway (5 participants), Massachusetts.

Study Method

Following specifications proven in previous studies,1, 2 we delivered a tailored lighting intervention (TLI) designed and specified to provide a robust light–dark pattern to maximally stimulate the human circadian system based on the mathematical model of CS developed by Rea and colleagues.3, 4 Our research has shown that providing a criterion CS value of 0.3 improves sleep, mood, and behavior in ADRD and PD patients.5, 6 The TLI employed three device modes (light tables, light trays, and retrofitted ambient room lighting [Figure 1]) over two 8-week intervention periods separated by a 4-week washout. The TLI’s (high CS) efficacy was compared to that of a non-therapeutic placebo (control) lighting intervention (low CS), and both lighting conditions were compared to baseline data collected in the existing facility lighting at the beginning of each 8-week intervention period (Figure 2). The study participants wore actigraphs on their wrists and completed questionnaires assessing depression, sleep quality, and sleep disorders during the first (baseline) and final assessment weeks of the two intervention periods.

Figure 1. The TLI modes used in the study: light table (left), light tray (middle), and retrofitted ambient room lighting (right).

Figure 2. The experimental protocol followed at the Medway facility. The experiment at the Westborough and Northborough facilities followed the same protocol and occurred between July and December 2022.

TLI Modes

Light tables. Custom-built light tables (XtraLight, Houston, TX, USA) were used at the Westborough site. The tables measure (l × w × h) 156 cm × 99 cm × 13 cm, with a luminous area on the tabletop measuring 137 cm × 79 cm and sitting 76 cm above the floor. The light is provided by 13 lightemitting diode (LED) strips measuring (l × w) 61 cm × 6 cm (model BB0040, ver. 001.1, XtraLight) recessed 9.5 cm beneath the tabletop and covered by a 1 cm thick diffused acrylic lens that serves as the table's durable work surface. The active TLI (measured in the lab) provided 1887 lx and a CS of 0.625 at eye level, and participants were encouraged to sit at the light tables whenever they were using the facility’s dining/community room.

Light trays. Light trays serving as light-emitting dining/work surfaces and fashioned after a conventional cafeteria tray were used at the Northborough site. Custom built by the LHRC, the trays house an LED array and measure (l × w × h) 64 cm × 53 cm × 4 cm. The participants were assigned to seats facing the tabletop light trays for breakfast and lunch over the course of the study. As measured in the laboratory at eye level when seated with a single dinner plate occluding the tray's surface, the active intervention delivered 602 lx and a CS of 0.456 and the control condition delivered 65 lx and a CS = 0.064. As the trays could deliver only a single condition, they were alternated between the active intervention and the control.

Ambient room lighting. The retrofit of the dining/community room lighting at the Medway site was performed with assistance from the researchers. In the area that received the retrofitted lighting, the mean illuminance measured at the eyes for occupants seated at the tables was 307 lx and the mean CS value was 0.28. The retrofit employed six 30-in diameter dimmable, direct/indirect circular (5-in lens aperture) ring pendant lighting fixtures (3000 K; Sketch, Axis Lighting, Lasalle, QC, CA) suspended over the dining/community room's six tables and four 4-ft linear dimmable, direct/indirect (2-in lens aperture) (3000 K; Beam 2, Axis Lighting) fixtures mounted on adjacent, opposing walls. The retrofitted system was driven by a programmable power/relay pack and on-screen controls (Acuity Brands, Conyers, GA, US) to deliver a CS of 0.4 from 07:00 to 17:00, gradually transitioning (from 17:00 to 18:00) to a CS <0.1 from 18:00 to bedtime. As confirmed via spectroradiometer, the actual average vertical illuminance (measured at eye level when seated at the table) was 520 lx (mean CS = 0.37) for the intervention lighting and 135 lx (CS = 0.1) for the control condition.

Results

The actigraphy data showed that participants slept significantly longer under the active condition after the TLI compared to baseline (p = 0.02) and sleep start time was significantly earlier after the TLI compared to baseline (p = 0.01). The questionnaires revealed that sleep quality scores improved significantly after the TLI compared to baseline under the active condition but not under the control condition (p = 0.01 and p = 0.24, respectively). Depression scores also improved after the intervention compared to baseline under the active condition but not under the control condition (p = 0.01 and p = 0.48, respectively), as did the sleep disturbance frequency and severity scores after the intervention compared to baseline under the active condition (p = 0.02). The sleep disturbance frequency and severity scores also increased after intervention compared to baseline under the control condition (p ≤0.03). The results are summarized in Table 1.

Table 1. Summary of results. The bold arrows enclosed in circles represent statistically significant results. Better outcomes are shown in green, worse outcomes are shown in red.

Takeaways

The key takeaways from this study are:

• Bright days, dim evenings, and dark nights improve sleep and mood in dementia patients, regardless of what metric you use or how you deliver light to the eyes.

• Don’t start with the lighting system, start with the patient’s daily activities and tailor the intervention so that the light is being delivered to each person passively.

• Ceiling lights delivering direct/indirect light can be used to deliver circadian-effective light. If the budget does not allow for tunable systems, simply use dimmers so light levels can be increased during the day and reduced in the evening.

• Be creative and think beyond the ceiling! The smaller size and flexible characteristics of LEDs can help designers create innovative ways to deliver circadian stimulus in a comfortable and effective way.

Acknowledgments

The authors wish to acknowledge Barbara Plitnick, Allison Thayer, Charles Jarboe, and Rohan Nagare of the Light and Health Research Center at Mount Sinai for their technical assistance, Diane Tonelli of Salmon Health & Retirements for logistical assistance, and the participants and their families. This research was funded by the National Institute on Aging (R01AG034157 and 2R44AG060857).

References

1. 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. J Clin Sleep Med. 2019;15(12):1757-67. doi: 10.5664/jcsm.8078

2. 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. J Alzheimers Dis Rep. 2020;4(1):297-312. doi: 10.3233/ADR-200212

3. Rea MS, Nagare R, Figueiro MG. Modeling circadian phototransduction: Retinal neurophysiology and neuroanatomy. Front Neurosci. 2021;14:1467. doi: 10.3389/fnins.2020.615305

4. Rea MS, Nagare R, Figueiro MG. Modeling circadian phototransduction: Quantitative predictions of psychophysical data. Front Neurosci. 2021;15:44. doi: 10.3389/fnins.2021.615322

5. Figueiro MG, Plitnick BA, Lok A, Jones GE, Higgins P, Hornick TR, et al. Tailored lighting intervention improves measures of sleep, depression, and agitation in persons with Alzheimer's disease and related dementia living in long-term care facilities. Clin Interv Aging. 2014;9:1527-37. doi: 10.2147/CIA.S68557

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(4):322-30. doi: 10.1016/j.sleh.2015.09.003

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