Phasor diagrams with light and activity profiles. Individual phasors (black lines) are shown with the average phasors (arrows) for each of the three groups, (a) healthy adult subjects studied during winter, (b) a group of subjects with ADRD studied during winter, and (c) another group of ADRD subjects studied during summer. Representative 5-day average light (CS, gray) and activity (AI, black) profiles are shown for a selected individual from each group (a–c). The representative individuals are those having the median phasor magnitude within each group.