Abstract
The aim of the present thesis was to examine the impact of fatigue on daily mood, and moderators of this impact, among people living with rheumatoid arthritis (RA) and university students. In the RA study, 73 RA patients completed paper-and-pencil diaries four times per day for seven days. In the student study, 637 undergraduate university students completed electronic diaries every evening for 13 days. Daily fatigue was associated with a less positive and a more negative mood on the same-day for RA patients and university students. RA patients with higher baseline anxiety and depression had a worse mood on high-fatigue days. University students with higher neuroticism had a worse mood on high-fatigue days. When RA patients were more physically active on high-fatigue days they were protected against large decreases in positive mood which were seen when RA patients were less physically active on high-fatigue days. Within-day lagged analyses revealed that negative mood in the morning predicted worse fatigue later in the afternoon for RA patients. In reverse, worse fatigue in the morning predicted a less positive mood in the afternoon, but only for RA patients with higher baseline anxiety. Taken together, the findings demonstrate that fatigue influences how RA patients and university students feel emotionally on a daily basis. The consequences of fatigue differ depending on how active, anxious or depressed RA patients are, and how neurotic university students are. The findings are discussed in relation to general and RA-specific theories of fatigue. The specific daily and within-day patterns have implications for developing interventions to ameliorate fatigue, and the moderation results indicate for whom such interventions may be most useful.