Light levels, primary and secondary measurements are obtained after a 4-week intervention period where active lighting is experienced by patients.

Light levels, primary and secondary measurements are obtained after a 4-week intervention period where an inactive lighting is experienced by patients

Subjects experience a baseline for 1 week and an active intervention for 4 weeks. The active intervention is a bluish white light source delivering at least 300 lux at the eye of the patient during at least 2 hours daily.

Caregivers and subjects are asked to complete the Pittsburgh Sleep Quality Index (PSQI), which is assessed at baseline and after 4 weeks they are exposed to the lighting intervention. The seven component scores are summed to provide a global score ranging from 0 to 21 and a score of 5 or above indicates sleep disturbance. A higher number indications a greater sleep disturbance

Caregivers and subjects are asked to fill out the Cohen-Mansfield Agitation Score, which is assessed at baseline and after 4 weeks they are exposed to the lighting intervention. All scores are summed for one total score - a higher score indicates more agitation

Caregivers and subjects are asked to fill out subjective questionnaires assessing depression using the Cornell Scale for Depression in Dementia (CSDD) Questionnaires are assessed at baseline and after 4 weeks they are exposed to the lighting intervention. The CSDD consists of 19 questions rated on a scale of 0 to 2 with all scores summed for a total score. A score greater than 12 indicates depression and a higher score indicates greater depression.

Caregivers and subjects are asked to fill out subjective Activity of Daily Living questionnaire (MDS-ADL), which is assessed at baseline and after 4 weeks they are exposed to the lighting intervention. Scores range from 4 to 18 and a higher score indicates a higher dependence.