Details

Autor(en) / Beteiligte

• Guu, Ta‐Wei
• Aarsland, Dag
• ffytche, Dominic

Titel

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

Ist Teil von

• International journal of geriatric psychiatry, 2022-05, Vol.37 (5), p.n/a

Ort / Verlag

England: Wiley Subscription Services, Inc

Erscheinungsjahr

2022

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• 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. Key points This article explores the evolution of scientific hypothesis about “sundowning syndrome”, or the diurnal‐nocturnal variation of behavioural and psychological symptoms in dementia (BPSD) and tries to elucidate the contribution of environmental light's image forming (IF) and non‐image forming (NIF) functions to the syndrome. Studies focussing on inadequate environmental light exposure in care home dementia patients and their behavioural rhythm and BPSD are reviewed. Correcting insufficiency in ambient light might be helpful to alleviate BPSD, which is likely associated with both the IF and NIF functions of light. There was a paucity of evidence on the role of IF light in relation to the specific BPSD symptom of visual hallucinations. Based on currently available evidence, we propose a novel model for BPSD and sundowning syndrome integrating light's IF and NIF effects and discuss the emerging evidence related to the invisible light spectrum.