Recommendations for measuring non-image-forming effects of light: A practical method to apply on cognitive impaired and unaffected participants.

BACKGROUND The non-image-forming effects of luminous radiation on people with intellectual disabilities or dementia received attention from researchers. Such studies, however, have generally been conducted using disparate methodologies which precludes generalization and reproducibility. OBJECTIVE The aim of this study was to determine the practical applicability of measurement devices for studies investigating non-image-forming effects of luminous radiation, specifically for people with intellectual disabilities or dementia. METHODS In three experiments, ten cognitive impaired people and thirty-nine unaffected subjects participated by wearing one or more portable devices. Six devices were assessed in total. Measurement data was accompanied with user experiences obtained from questionnaires, interviews and observations in order to assess the devices on practical and comfort issues. RESULTS On average, the devices worn by the cognitive impaired subjects were not experienced as annoying or irritating. No significant differences are found between genders and for one of the portable devices significantly less annoyance was reported by the cognitive impaired participants compared to the unaffected group of participants. INNOVATIVE SOLUTION The three phases of the research process in towards measuring personal luminous exposures are: selection of the most suitable portable device, application of the assessment method, and the application of the device in the (pilot) study. CONCLUSIONS However, the findings of this study suggest that inaccuracies potentially caused by practical and comfort issues associated with the portable devices need to be considered.