Both fibromyalgia (FMS) and rheumatoid arthritis (RA) are chronic pain conditions, can disrupt sleep, and result in subjective daytime sleepiness and fatigue. This article discusses a comparison between the two conditions with regard to objective sleep quality at night and daytime sleepiness in women. Researchers did standard sleep studies and surveyed the patients for their subjective experiences.
The results showed that there was similar nighttime sleep disturbance between those with FMS and RA. The FMS patients reported greater subjective daytime sleepiness and fatigue than those with RA. But the sleep studies showed relatively low daytime sleepiness in FMS and an intermediate amount in the RA patients.
These results support clinical findings - that FMS patients are generally not sleepy, but very fatigued. Fatigue can not be measured like sleepiness. Patients with RA are more sleepy, and this is supported with objective testing. RA patients are also fatigued. The authors of the study concluded that FMS patients have less sleepiness and more fatigue due to hyperarousal. This could be true, but unfortunately it is difficult to treat.