Although patients with rheumatoid arthritis (RA) and those with severe seasonal allergy appear to have sleep alterations, inflammation may not be an independent predictor of the sleep disturbance, according to results of a study published in Nature and Science of Sleep.
An exploratory study was conducted in Sweden to examine objective and subjective sleep disturbances in individuals with allergy and RA and the effect of sleep measures on markers of inflammation.
Researchers used sleep diaries, one-channel electroencephalography (EEG), and actigraphy to evaluate sleep among the study participants. Researchers also evaluated whether sleep measures were linked to central immune activation, using translocator protein (TSPO) positron emission tomography (PET), along with cytokine markers of peripheral inflammation, disease-specific symptoms, and general symptoms of sickness.
The study included a total of 18 individuals with seasonal pollen allergy, 18 patients with RA, and 26 healthy control participants. Data from patients with allergy and matched control participants were evaluated twice, both in and outside of the pollen season; data from patients with RA were assessed once. Sleep was also recorded each time for approximately 1 week.
Results of the study showed that individuals with seasonal allergy vs healthy participants had a shorter total sleep time (TST), according to the EEG readings, across the seasons. Individuals with allergies also demonstrated an increase in the percentage of slow wave sleep (SWS) during the pollen season. Patients with allergy vs control participants had worse sleep quality during the pollen season. In addition, morning sleepiness was enhanced among individuals with allergies during the pollen season.
Based on sleep diaries, TST did not differ between the groups. Further, when decomposed, patients with allergies showed a significant increase in absolute SWS time during the pollen season (+8.79 min; P =.01), whereas the control participants did not (-2.42 min; P =.34).
The TST did not differ between patients with RA and control participants, according to sleep diaries and the EEG. Patients with RA vs control participants had significantly shorter sleep, but not deep sleep, light sleep, and rapid eye movement sleep. There were no significant differences observed between the groups regarding sleep efficiency or number of awakenings.
Compared with control participants, patients with allergy did not exhibit significantly higher levels of sickness symptoms (P =.970), and the interaction with pollen season was not significant (P =.089). However, patients with RA vs control participants reported significantly higher levels of sickness symptoms (P =.008). Moreover, no significant associations were observed between symptoms of sickness and TST, amount of deep sleep, or subjective sleep quality.
Across the groups, proinflammatory cytokines, grey matter TSPO levels, and general sickness symptoms were not associated with objective or subjective measures of sleep. However, rhinitis, but not conjunctivitis, was linked to worse subjective sleep and more SWS in individuals with seasonal allergy. In patients with RA, functional status, but not disease activity, was predictive of lower subjective sleep.
The main study limitation was the relatively small sample size.
Researchers concluded, “This study corroborates earlier findings that both patients with seasonal allergy and RA suffer from sleep alterations in addition to their primary symptomatology.”
Disclosure: Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Tamm S, Lensmar C, Andreasson A, et al. Objective and subjective sleep in rheumatoid arthritis and severe seasonal allergy: preliminary assessments of the role of sickness, central and peripheral inflammation. Nat Sci Sleep. 2021;13:775-789. doi:10.2147/NSS.S297702