For evening fatigue, the FCs’ baseline level of sleep disturbance, as well as the patients’ baseline level of evening fatigue predicted inter-individual differences in evening fatigue severity at the time of the simulation visit (i.e., intercept). When the other predictors were held constant, FCs’ evening fatigue scores ranged from 2.69 to 6.57. Of note, for every one unit increase in patient’s evening fatigue scores, FCs’ level of fatigue increased by .35 units which is consistent with a previous report (Curt et al., 2000). However, our findings differ from those of Passik & Kirsh (2005), who found no relationship between patients’ and FCs’ (n=25) fatigue scores. These differences may be related to the larger sample size in our study. In addition, the patients’ baseline level of morning fatigue predicted FCs’ baseline level of morning fatigue. Taken together, these findings suggest that studies of symptoms in FCs need to include an evaluation of symptoms in the patients, particularly if the purpose of the study is to determine the predictors of symptom severity in FCs.