Sleep and circadian rhythm disturbance are predictors of poor physical and mental health, including dementia. Long-term monitoring of sleep and circadian rhythms in people living in the community may have great potential for early diagnosis, monitoring of disease progression and assessing the effectiveness of interventions in dementia and other health conditions. Many novel digital technology-based approaches for monitoring sleep and circadian rhythms, aimed at both the consumer and research markets, have recently become available. However, before such technology can be implemented at scale, its performance and acceptability need to be evaluated and compared to established gold standard methodology in relevant populations.Here we describe a protocol for the evaluation of novel sleep and circadian technology in cognitively intact older adults, some of whom have stable comorbidities, and in people living with dementia (PLWD). In this protocol a range of technologies is tested simultaneously first at-home during a one- to two-week period and subsequently in a clinical research facility in which gold standard methodology for assessing sleep and circadian physiology is implemented.We emphasize the importance of assessing both nocturnal and diurnal sleep (naps), valid markers of circadian physiology, and that evaluation of sleep and circadian technology is best achieved in protocols in which sleep is mildly disturbed and in populations and settings that are relevant to the targeted use-case. We provide details on the design, implementation, and challenges of this sleep and circadian technology evaluation protocol along with examples of the datasets that have been generated in both cognitively intact older adults and PLWD. We place our protocol in the context of existing literature and highlight the benefits that our methodology has over previous approaches.Author SummarySleep and circadian (24-hour) rhythms are frequently disrupted in various physical and mental health conditions including dementia. These disturbances may merely be an outcome of the disease process or be drivers of disease progression. Either way, the ability to monitor sleep and circadian rhythms long-term and at-home could be highly beneficial for monitoring health status, early identification of decline, and implementation of interventions as well as monitoring the effectiveness of interventions. A number of new digital health technologies are now available that could allow non-invasive, non-intrusive, long-term monitoring of sleep and circadian rhythms at home. However, few of these have been evaluated against gold-standard measures in a relevant population. Here we describe our approach to simultaneously evaluating multiple types of sleep and circadian technologies against standard methodology, both at-home and in the laboratory, in a group of older adults with and without dementia. We discuss the feasibility of this protocol, provide examples of the data that were obtained, the data analyses and visualisations that can be applied, and explain the benefits of our approach.