Light, sleep‐wake rhythm, and behavioural and psychological symptoms of dementia in care home patients: Revisiting the sundowning syndrome

Abstract

Objectives It is believed that inadequate environmental light, especially in facilities such as care homes, contribute to the diurnal changes of behavioural and psychological symptoms of dementia (BPSD) historically referred to as “sundowning syndrome”. Conceptual models of sundowning phenomena have shifted emphasis from the role of light in vision (image forming) to its role in circadian rhythm modulation. However, the grounds for this change are unclear and the evidence on which it is based has not been examined comprehensively. Methods We have searched literature on sundowning syndrome and its association with light and studies evaluating BPSD, behavioural rhythm and environmental light in care homes in four databases (PubMed, Web of Science, Embase and Cochrane Library) from inception to 31 January 2021. Results Of the nine studies investigating light, behavioural rhythm and BPSD in care homes identified, we found evidence that insufficient natural light exposure was associated with worsening of BPSD and disrupted activity rhythm but it was not clear whether this related to image forming or disrupted circadian rhythm. There was a paucity of evidence in relation to the role of low levels of light for image forming in the context of a specific BPSD symptom: visual hallucinations. We also found literature on the possible role of light outside the visible spectrum influencing cognition. Based on the evidence, we proposed a new model integrating different components of light in BPSD and sundowning syndrome that combines its image forming and circadian roles. Conclusions Inadequate light may be a risk factor for BPSD and sundowning syndrome for dementia patients through a range of different mechanisms. It is recommended that multiple neuro‐endocrinological and socio‐environmental factors relevant to light such as adjusting the environmental setting, increasing light exposure, and scheduling activities should be considered when treating dementia patients with BPSD.

Association between Sleep and Alzheimer’s Disease: A Bibliometric Analysis from 2003 to 2022

“…Sundown syndrome, commonly seen in AD, is characterized by increased incidence of neuropsychiatric symptoms such as anxiety, confusion, and irritability in the evening, and thus affects the sleep quality [22]. The exact cause of sundown syndrome remains unknown, but findings indicate it may be related to short sleep duration and circadian rhythm disturbances [23]. Moreover, long-term lack of sleep can cause cognitive dysfunction and aggravate the occurrence of neuropsychiatric symptoms in affected individuals [24].…”

Effect of Personalized Blue-Enriched White Light Intervention on Rest–Activity and Light Exposure Rhythms in Mild and Moderate Alzheimer’s Disease

“…Meanwhile, behavioral and psychological symptoms of dementia, such as sundowning, might be a phenomenon that reflects a breakdown of circadian rhythmicity. 15,16 A therapeutic effect of light intervention on sleep and behavior in AD patients may be related to the ability of such intervention to alleviate their circadian disturbances. 17 Moreover, light interventions may have advantages over pharmacological treatments in terms of their side effect profiles for people with dementia.…”

Melatonin’s Benefits and Risks as a Therapy for Sleep Disturbances in the Elderly: Current Insights

“…“Sundowning”, a chronobiological dysfunction reported in AD, is one such developing symptom. 87 Sundowning symptoms include disordered thinking, a reduced ability to pay attention to external stimuli, agitation, wandering, and perceptual and emotional abnormalities, all of which manifest in the late afternoon or early evening. Strong light exposure and timed melatonin delivery at specific circadian times relieved sundowning symptoms and improved sleep-wake patterns in AD disease patients.…”