###### Abstract
Studies focusing on persons with dementia still living at home are extremely scarce [26; 27; 21]. [PERSON] [27] concluded in a review article on interventions for people with dementia at home that light therapy is a promising strategy to alleviate the circadian disturbances and improve the well-being of people with dementia. It is important to note, though, that these studies used a variety of light therapy approaches and do not always report explicitly how the light doses received by the participants were measured or monitored. As [PERSON] et al. [21] concluded, it is one of the biggest future challenges to find a suitable and practical method for effectively delivering brighter daytime light to the eyes of people with dementia still living at home. It is difficult to conduct light research on people with dementia living at home because of the heterogeneous population, living circumstances, diffuse nature of the disease, and practical objections, such as being proficient in the use of devices. In addition, to measure the effect of a lighting intervention, participants need to be followed over a long period of time. A longitudinal study design is difficult--in this population--and many variables may influence data collection. For example, a recent field investigation in an office context demonstrated that light interventions may be far less effective than hoped in terms of increasing personal light exposure, and that this effectiveness is substantially influenced by contextual and behavioral factors [28]. It is therefore essential to take into account the individual user and his or her context. The individual characteristics, living situation, and dementia stage may all play a role in the practical feasibility of implementing light innovations in a home situation. Randomized placebo-controlled trials (RCTs) are still considered the gold standard in medical research, but naturally, they also have limitations. RCTs have strong internal validity, but their external validity often remains inadequate. The generalization of findings outside of the study group is, by no means, always justified. There is little \"real-life evidence\", and the transition from group evidence to evidence relevant to the treatment of individuals cannot be made. There is no focus within an RCT on the influence of individual patient characteristics, and a heterogeneous group, such as patients with dementia, is hard to study properly using this design. A disadvantage of other study designs, however, is that without randomization in daily practice, it is difficult to reliably link positive effects to an intervention. In addition, researchers would like to be able to compare new interventions with existing ones. Field studies on dementia are challenging. However, to determine what functional specifications an innovation requires to support patients with dementia and to find out in practice whether this system is experienced as effective, real-life or field studies are necessary and valuable. In several real-life studies [20; 25; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39], caregivers of patients with dementia have pointed out the need for support. Technological systems could be a solution to the problems they encounter, such as getting lost and wandering behavior at night due to circadian disruption. It seems that patients who are in an early stage of dementia would profit the most from these technological devices [33; 34; 35; 36]. Therefore, in the current study a real-life single-case experimental design (SCED) was chosen in which the results were analyzed by randomization testing. In doing so, a combination of the advantages of an RCT and the advantages of a real-life field study was attempted. The ecological validity of this study design is high as lessons are learned and shared in the design of a sustainable research protocol. It is necessary to evaluate whether the applied SCED and the methods of data collection and data analysis are applicable for measuring the effect of dynamic lighting on people with dementia living at home.