What type of lighting promotes positive mental health for ageing and dementia populations? A debate on the conflicting priorities and pathways for technology,

With the extended use of LED technology in the modern era, light has the capacity to both enhance and impair wellbeing for the ageing population and people living with dementia. While daylight is beneficial for our circadian health, artificial lighting technologies can influence physical and emotional wellbeing to varying degrees depending on their spectra, timing and duration of exposure.Ageing is a risk factor for developing dementia, but it also increases the risk of developing certain visual deficiencies such as age-related macular degeneration, glaucoma or cataracts. The individual demands of lighting must then cater to these visual requirements while ensuring that dementia-related symptoms such as sundowning, agitation and disrupted sleep are not negatively impacted. This can become complex to achieve since these lighting requirements often conflict with one another resulting in a compromise in some aspect of overall wellbeing.This then poses the question; if lighting requirements differ for vision, sleep, task completion, hobbies, alongside other behavioural and psychological symptoms of dementia, what aspect of wellbeing do we prioritise when designing lighting for this population? Where vision has a significant influence over gait, stability and falls, should this take precedence over circadian stability which promotes better mood and sleep? Should brighter task lighting required for engaging in hobbies outweigh the risks of overstimulation and increased agitation?Modern luminaires and electronics use tuneable and dimmable LED technology to automate solutions to these scenarios. However, does automation best serve those who experience cognitive decline and are at risk of forgetting to adjust their environmental settings, or is the autonomy of manual control more empowering? The answers to these questions will likely reside in how we define wellbeing and the weight of the overlap between good physical and good mental health. This research therefore seeks to engage in a debate on whether the perfect balance of light for this cohort does in fact exist while highlighting the need for flexibility and personalisation of lighting technologies to address these matters in the future.