Figure 2. Assessment of fluctuation in fatigue scores using environmental data.

The relationship between fatigue (as measured by the Modified Fatigue Impact Scale [MFIS]) and hours of daylight is presented for patients with multiple sclerosis (MS) in (A) and cohabitants in (B). Each participant is represented by one line describing the relation between MFIS and daylight hours. For most participants, there is no significant correlation between fatigue and hours of daylight (represented by gray lines); however, 4 participants represented by colored lines do show a significant increase in MFIS with more hours of daylight, and 1 participant shows the opposite, highlighting the symptomatic heterogeneity among patients with MS. (C) The MFIS total score for patients with MS is presented over the course of the calendar year. Each MS study completer is represented by a different line.