Variability of fatigue during the day in patients with primary Sjögren's syndrome, systemic lupus erythematosus, and rheumatoid arthritis.

OBJECTIVES Fatigue is a common complaint of patients with primary Sjögren's syndrome (pSS), systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA). The aim of this study was to examine and compare in patients with these diseases the course of fatigue within the first hour after awakening and during the day, and to examine sleep disturbance as a potential determinant of fatigue. METHODS Eight repeated measurements at 5 fatigue dimensions were assessed on 2 consecutive days in the natural environment of female patients with pSS (n=29), SLE (n=23), RA (n=19), and healthy women (n=52). Sleep disturbance of the previous night was assessed. Fatigue levels and the change of fatigue after awakening and during the day were analysed with analyses of variance (adjusted for age). RESULTS The patients showed significantly elevated levels at all fatigue dimensions as compared to healthy participants. Fatigue levels decreased in the first hour after awakening in patients with SLE and RA, but increased or did not change in patients with pSS. Fatigue progressively increased during the remainder of the day for all patient groups. Sleep disturbance correlated with overall fatigue levels, but hardly with the change of fatigue within the first hour after awakening. CONCLUSIONS Our study confirms the presence of increased fatigue in patients with pSS, SLE, and RA. Patients with pSS failed to show a decrease in fatigue in the first hour after awakening. Future research should examine the causes of this difference in fatigue after awakening.