Introduction: The increase of neuropsychiatric symptoms in people with dementia count for 46% of the transit to more controlled environments. Medication to repress these symptoms is widely used, but the side effects are significant, and the effect at start is not predictable. Research that aims at non-pharmacological interventions is important. One of the promising non-pharmacological interventions is lighting. In this study the effectiveness of biodynamic lighting, lighting with variable intensity and color, on neuropsychiatric symptoms in people with dementia is studied. It was hypothesized that the exposure to biodynamic lighting would decrease the amount and/or the severity of the neuropsychiatric symptoms. Method: A biodynamic lighting innovation designed to stimulate a regular and healthy circadian rhythm was installed in the common area of a clinical setting. Two conditions of 21 days with and 21 days without exposure to biodynamic lighting were monitored. After each condition, measures of presence, severity of symptoms and emotional impact were collected using the Neuro Psychiatric Inventory-Questionnaire (NPI-Q). Results: Eighteen participants were included in the research and completed a condition with and without exposure to biodynamic lighting. Per respondent the total index of severity of neuropsychiatric symptoms was lower after exposure. Also on a group level a tendency (p=.187) was found for decreasing the total index of severity of the neuropsychiatric symptoms in the condition that received biodynamic lighting. Significance was only found in the severity scores on the symptom disinhibited behavior (p=.01). Conclusion: A biodynamic lighting intervention can be used to decrease the severity of neuropsychiatric symptoms, more specific disinhibited behavior. This is important because disinhibited behavior is related to a disturbed circadian rhythm, is distressing for caregivers and can accelerate the process leading to institutionalization. The findings in this study implicate the importance of future research on the possibilities of biodynamic lighting in dementia.

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