A chronically low sleep duration was associated with an increased risk of systemic lupus erythematosus (SLE), according to a study published in Arthritis Care & Research.1 Stronger effects were reported in patients with bodily pain and depression, emphasizing the possible link between sleep and disease prevention.
“Several small case-control and cohort studies have provided conflicting results on the relationship of sleep duration and SLE risk,” investigators noted. “A challenge in studying sleep duration and SLE is that there may be many potential confounders and effect modifiers, including pain, depression, shiftwork, and hormonal status, that need to be considered. Furthermore, sleep disturbances in established SLE are common, and active disease has been associated with sleep fragmentation, which in turn, may induce sleep deprivation.”
Average sleep duration in a 24-hour period was determined using 2 large groups of women enrolled in the Nurses’ Health Study (NHS) and Nurses’ Health Study II (NHSII) cohorts. Data on demographics, clinical data, and exposure were obtained via biennial questionnaires. Patients without prevalent SLE or other connective disease (CTD) at baseline were excluded.
Adjusted Cox regression analyses identified potential links between cumulative average sleep duration and incident SLE. Connections between sleep duration and shiftwork, depression, and bodily pain, as determined by the Short-Form 36 questionnaire (SF-36) were evaluated.
Of the 186,072 women analyzed, there were 187 incident SLE cases during 4,246,094 person-years of follow-up. Women with shorter sleep duration were more likely to exercise regularly, consume less alcohol, had higher bodily pain, and reported a younger age of menarche. Chronic low sleep duration, as defined by ≤5 hours/night, was linked to an increased risk of SLE (adjusted hazard ratio [HR] 2.47, 95%CI:1.29-4.75), which was sustained after the analysis lagged (4 years, adjusted HR 3.14, 95%CI:1.57-6.29). An almost 3-fold elevated risk of SLE was shown among women with low sleep, depression (AP of 68% [95% CI 49-88%]), and bodily pain (SF-36 < 75) when compared with those without these concomitant issues (adjusted HR 2.13, 95%CI:1.11-4.10). Further, additive interactions between low sleep duration and high bodily pain (SF-36 <75) were identified with an attributable proportion (AP) of 64% and HR for SLE of 2.97 for people with both risk factors when compared with those with neither.
The NHS cohorts are well-described with up to 5.8 million person-years of follow-up. Potential time-varying confounders further reduce variation, inaccuracy, and the possibility of reverse causation and recall biases. Confounders, such as depression and pain, were also accounted for in the analysis. However, the small number of SLE cases in some sleep categories, as well as the majority of patients self-reporting as White females, limited generalizability. As questionnaires were utilized, there may be unknown confounders that were not included in the analysis.
“A better understanding of the mechanisms involving the nervous system and immune system that may be underlying the complex interaction between depression, pain, sleep, shiftwork, and autoimmune disease development is needed,” investigators concluded. “Our findings have implications for SLE prevention and the promotion of adequate sleep duration.”
Choi MY, Malspeis S, Sparks JA, Cui J, Yoshida K, Costenbader KH. Association of Sleep Deprivation and the Risk of Developing Systemic Lupus Erythematosus among Women [published online ahead of print, 2022 Sep 12]. Arthritis Care Res (Hoboken). 2022;10.1002/acr.25017. doi:10.1002/acr.25017