Introduction: We know that blue light can improve health and well-being, but can we recommend an optimum exposure, either from daylight or by artificial intervention, if we do not know to what extent exiting environmental blue light impacts on humans? Specifically, the research question is to assess the exiting blue light component, in an elderly person care home, and the possible impacts on sleep and cognition for both those with and without dementia.

Background: The aim of the project is to explore the most effective time and duration of blue light exposure (BLE) to help promote good sleep, health and well-being in older people and those with dementia or Alzheimer’s The impact of light and its abilities to be used as a non-pharmaceutical method of regulating sleep and reducing some of the symptoms associated with Alzheimer’s and dementia is an established field (Shochat et al 2000, McCurry et al 2005). In particular, it has been found to be the shorter wavelengths (i.e. the blue light) which help to synchronize our body clock, regulate hormones, maintain alertness during the day and influence patterns of sleep at night (Holzman 2010). However, what is not known is what degree of exposure to blue light (in terms of both its intensity and time of day) is most effective in promoting good sleep in older people and those with dementia or Alzheimer’s.

Subjects: An estimated cohort of 30-40 older people in care homes will have their rest-activity patterns and BLE monitored continuously for a 4-day period. Severity of dementia impairment (also type i.e. Alzheimer’s disease, vascular dementia etc.) will be assessed using the Neuropsychiatric Inventory for Nursing Homes and Clinical Dementia Rating and a short reaction time test will be conducted.

Apparatus: Each participant will wear an actigraph watch, Phillips Respironics Actiwatch Spectrum, continuously. This records rest-activity patterns and incorporates a light sensor to monitor red, green, blue and white light exposure. Light and activity levels will be sampled at 15-second epochs.

Procedure: The participants will be met with individually to explain the study and carry out appropriate assessments and cognitive test. The actiwatch will be secured to the participant’s wrist and shall be calibrated to begin recording at 12noon on day 1 and then removed at 12noon on day 4. This study will be carried out in winter 2013-2014 and again in summer 2014.

Data analysis: Actiwatch software will be used to define various epochs of times and durations of exposure. In SPSS a one-sample t-test, non-parametric correlations and simple regression model will look for statistical significances.

Preliminary findings from a pilot study: We have carried out a pilot study, in which we applied this protocol to 6 older people in a care home, 4 with and 2 without dementia. Early indications are for non-dementia participants – improved sleep efficiency and more consolidated nocturnal sleep, exposure to higher lux levels and increased activity levels during the day, whilst for dementia participants – experienced fragmented and poor sleep efficiency, with frequent periods of light turned on and lower daytime activity levels.

Discussion: The rationale behind the study is to begin to quantify daytime BLE of dementia patients and give a better understanding to the most effective time and duration of exposure. This will highlight possible deficits in BLE and provide the opportunity to assess associations with sleep, cognition and to better appraise an intervention study.