The present study examined the within-day relationship between fatigue and positive and negative mood among adults with rheumatoid arthritis (RA) or osteoarthritis (OA).
A sample of 142 adults-70 with RA and 72 with OA (67.6% women, 32.4% men)-completed daily diaries during 4 fixed time windows per day for 7 days. In each diary, participants reported fatigue, pain, happiness, and frustration. Multilevel modeling tested the temporal patterns in fatigue across the day and the lagged associations between fatigue and subsequent mood (and vice versa).
Fatigue showed a midmorning dip followed by a linear rise in the afternoon and evening. Higher fatigue earlier in the day predicted subsequently lower happiness and higher frustration. Higher frustration-but not happiness-predicted subsequently worse fatigue. These within-day patterns were significant even when controlling for daily sleep quality, daily physical activity, diagnosis, age, gender, anxiety, depression, and disability.
There was a unidirectional effect of fatigue on subsequent happiness and a bidirectional relationship between fatigue and frustration within the same-day for adults with RA or OA. These findings inform interventions for the management of mood and fatigue throughout the day and suggest that addressing fatigue could improve mood, and that addressing sources of frustration could improve fatigue among people with arthritis.