## 4 Discussion
### Lessons Learned  
Based on this study, some lessons learned could be formulated for the implementation of the light protocol in practice. First, implementing a lighting system in the homes of people with dementia is possible and possibly useful. However, in sunny seasons, such as spring and summer, the added value of the lighting system compared with daylight is marginal. Therefore, it might be more useful to install the lighting system in darker seasons, such as fall and winter [25].  
Besides these seasonal effects, the results also revealed differential effects for the lighting system with respect to the parts of the day. The effect of the lighting system was most pronounced in the afternoon and mostly absent in the morning. This result may be explained by the fact that the participants tended to be more active and outside in the morning, receiving more natural daylight than in the afternoon and evening, when the sun had already set by 5:00 or 6:00 p.m. in the fall and winter months. The effects were also less in the evening, but this would be in line with recommendations and the dynamic scenario as evening light is generally considered bad for sleep. This might indicate that it is useful to emphasize to users to use the lighting system in the afternoon and evening and to stimulate these users to (continue to) go outside in the morning.  
The correlated color temperature did not significantly differ for the spectrometer results in the three rooms with and without the lighting system. This was likely causedby the fact that these measurements were taken late in the morning, when the correlated color temperature of the scenario was close to that of standard lighting. Across the day, the scenario varied between both higher and lower CCT values, so one would not necessarily expect large overall changes.  
Carefully designed technological interventions can respond to unmet needs of people with dementia and family caregivers at different stages as dementia progresses [49]. Existing products, systems, and services are often too complex to be used by people with dementia [50]. [PERSON] et al. [51] found that it is very important that innovations are supported by the users, are experienced as user-friendly, and are practically feasible in terms of successful implementation. Therefore, the development of assistive technology for people with dementia needs to be evaluated in a real-life context [52; 53; 54].  
Although the evaluation of the subjective experience of the lighting system by the participants is, of course, difficult because of the dementia, we were still able to gather information from most of the participants (6 out of 11) based on a short questionnaire. The vulnerability became painfully obvious with the fact that two of the people had passed away and two had moved to a care home shortly after the end of the study. The participants valued and missed the lighting system, the extra light exposure in terms of intensity and color and atmosphere, when removed. Moreover, the informal caregivers were positive, and most of them even reported a positive, though still subjective, effect on the sleep, activity, and psychological well-being of their loved ones. The vulnerability of the population and still the applicability and effect of the used study design indicate that the lighting system might be useful for people with dementia in moderate and severe stages of the disease. This seems an important finding as care innovations for home use are mostly developed and implemented by people with dementia in mild stages of the disease.