Patients with early rheumatoid arthritis (RA) have short sleep duration at night that is associated with cardiovascular disease (CVD) risk factors, according to study findings published in ACR Open Rheumatology. The theoretical reallocation of time from sedentary behavior or physical activity to sleep was associated with a decrease in CVD risk factors.
In the general population, lack of sleep is associated with CVD. In patients with RA, sleep disturbances are common and CVD is a main cause of death. This study assessed the association between sleep duration and cardiovascular (CV) health in patients with early RA. It also looked at the potential CV benefit of replacing other activities such as sedentary behavior, light physical activity, or moderate to vigorous physical activity with sleep.
This cross-sectional study included patients aged 75 and younger with early RA who had a disease duration of 12 to 24 months and were symptomatic less than 12 months before diagnosis. Activity behaviors were measured for 7 consecutive days using a wearable electrocardiogram (ECG) monitor. Researchers also collected CV risk factors from patient records and conducted body composition and pulse wave analyses. The theoretical consequences of replacing 30 minutes of 1 behavior with another were assessed using isotemporal substitution modeling adjusted for monitor wear time, age, and sex.
The median sleep duration per night was 4.6 (3.6 to 5.8) hours. Patients with longer durations of sleep had lower body composition measurements such as weight (b=-2.53; 95% CI,-3.94 to -1.12) and body mass index (b=-0.90; 95% CI, -1.38 to -0.40), sleeping heart rate (b= -0.80; 95% CI, -1.49 to -0.10), and blood pressure measurements (eg, systolic blood pressure, b= -2.49; 95% CI, -3.95 to -1.04).
An additional 30 minutes of sleep was associated with a 2.9%, 3.3%, and 2.3% decrease in body weight when substituted with 30 minutes of sedentary behavior, light physical activity, or moderate or vigorous physical activity, respectively; for systolic blood pressure, an additional 30 minutes of sleep was associated with a 2.6%, 3.0%, and 2.5% decrease, respectively.
Limitations of the study included its cross-sectional design, incomplete monitoring data (the average time on the monitor was 19.3 hours/day), and sleep data only being collected during the night vs daytime sleep or naps.
“To our knowledge, this is the first study among patients with RA to report associations between sleep duration at night and risk factors for CVD as well as to present the possible consequences of reallocating time between different activity behaviors on CV risk factors by performing isotemporal substitution modeling,” the researchers concluded. “Future studies are needed to clarify the causal relationships between sleep and CV health and to explore the longitudinal effects of sleep deprivation among these patients.”
Hörnberg K, Pomeroy J, Sandberg C, Ångström L, Södergren A, Sundström B. Isotemporal substitution of time between sleep and physical activity: associations with cardiovascular risk factors in early rheumatoid arthritis. ACR Open Rheumatol. 2021;3(3):138-146. doi:10.1002/acr2.11225