By 2030, a total of 20% of the United States population will be 65 years or older; and the prevalence of dementia in this population is approximately 10%.1 Circadian rhythm sleep-wake disorders, specifically irregular sleep-wake rhythm disorder (ISWRD), are highly prevalent in patients with dementia and neurodegenerative disorders. This may occur due to degeneration of the suprachiasmatic nucleus (SCN), which synchronizes our internal circadian rhythm with the environment.
Reduced light exposure seen with aging and dementia, with less time spent outdoors, poor indoor lighting, and decreased light sensitivity from age-related vision changes are contributory factors.2 Higher light intensity may be required to stimulate the SCN in patients with dementia.3 The American Academy of Sleep Medicine (AASM) recommends light therapy for the treatment of ISWRD in older patients with dementia, recognizing the important role that light has in improving outcomes in these patients.4
Effects of circadian rhythm disruption on sleep, activity, and cognition are interlinked with neuropsychiatric behaviors seen in this population.5 Sleep disruption occurs in 70% of patients with dementia, increasing risk of injury and imposing a high caregiver burden. Patients with Alzheimer disease spend much of the day sleeping and 40% of the night awake, often with symptoms of confusion, wandering, and agitation.6 Antipsychotics, which are frequently used in these patients, are associated with adverse effects and worse outcomes when compared with nonpharmacologic approaches.7
Notably, in a study involving patients with Alzheimer disease, increased mortality was seen in patients randomized to receive antipsychotics.8 Management of sleep-wake disruption and the associated behavioral and psychological symptoms in patients with dementia should involve safer and effective nonpharmacologic intervention alternatives. These include bright light therapy, cognitive behavioral therapy, physical exercise, therapeutic recreation, and strategies incorporating use of massage, music, reminiscing, and acupuncture.
Results from systematic reviews and metanalyses have shown small but significant improvement from light therapy in measures of sleep, cognition, mood, and behavioral disturbances in older adults with dementia in an institutional setting.3,5,9–10 Heterogeneity in the studies with regard to patient population and specifics of light therapy used—such as source, dose, spectral composition, timing, and duration—has limited comparison of the efficacy of therapy methods across studies. Most studies with improved outcomes used a minimum of 2,500 lux, delivered between 9:00 am and 12:00 pm for one to two hours. Lower intensities with longer exposure duration may be effective in patients with intolerance to higher light intensities.11 White broad-spectrum tabletop light boxes were more frequently used, although wall or ceiling-mounted lights, LED lights, and outdoor natural light can also be used.12
Per the AASM recommendation regarding treatment of ISWRD in older patients with dementia, a comprehensive approach combining light therapy with daytime physical activity and sleep-wake scheduling has significant benefits. Adverse effects of light therapy are typically infrequent, mild, and self-limiting, including eye strain, headache, nausea, and agitation. Bright light therapy is therefore a low-cost, nonpharmacological, safe, and feasible intervention with multidimensional benefits; this therapy should be incorporated into the management algorithm of older individuals with dementia.
References
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2. Sateia MJ. International classification of sleep disorders-third edition: highlights and modifications. Chest. 2014;146(5):1387-1394. doi:10.1378/chest.14-0970
3. Fong KN, Ge X, Ting KH, Wei M, Cheung H. The effects of light therapy on sleep, agitation and depression in people with dementia: a systematic review and meta-analysis of randomized controlled trials. Am J Alzheimers Dis Other Demen. 2023;38:15333175231160682. doi:10.1177/15333175231160682
4. Auger RR, Burgess HJ, Emens JS, Deriy LV, Thomas SM, Sharkey KM. Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders: advanced sleep-wake phase disorder (ASWPD), delayed sleep-wake phase disorder (DSWPD), non-24-hour sleep-wake rhythm disorder (N24SWD), and irregular sleep-wake rhythm disorder (ISWRD). An update for 2015: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2015;11(10):1199-1236. doi:10.5664/jcsm.5100
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7. de Oliveira AM, Radanovic M, de Mello PC, et al. Nonpharmacological interventions to reduce behavioral and psychological symptoms of dementia: a systematic review. Biomed Res Int. 2015;2015:218980. doi:10.1155/2015/218980
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9. Chiu HL, Chan PT, Chu H, et al. Effectiveness of light therapy in cognitively impaired persons: a metaanalysis of randomized controlled trials. J Am Geriatr Soc. 2017;65(10):2227-2234. doi:10.1111/jgs.14990
10. Zhang M, Wang Q, Pu L, et al. Light therapy to improve sleep quality in older adults living in residential long-term care: a systematic review. J Am Med Dir Assoc. 2023;24(1):65-74.e1. doi:10.1016/j.jamda.2022.10.008
11. Hjetland GJ, Kolberg E, Pallesen S, et al. Ambient bright light treatment improved proxy-rated sleep but not sleep measured by actigraphy in nursing home patients with dementia: a placebo-controlled randomised trial. BMC Geriatr. 2021;21(1):312. doi:10.1186/s12877-021-02236-4
12. Mishima K, Okawa M, Hishikawa Y, Hozumi S, Hori H, Takahashi K. Morning bright light therapy for sleep and behavior disorders in elderly patients with dementia. Acta Psychiatr Scand. 1994;89(1):1-7. doi:10.1111/j.1600-0447.1994.tb01477.x
