Sleep and physical activity: an objective profile of people who have rheumatoid arthritis
Sean McKenna 1, Marie Tierney 2, Aoife O’Neill 3, Alexander Fraser 4, Norelee Kennedy 1, 5
1. Department of Clinical Therapies, University of Limerick, Limerick, Ireland 2. Discipline of General Practice, National University of Galway, Ireland 3. Department of Mathematics and Statistics, University of Limerick, Ireland 4. Department of Rheumatology, University Hospitals Limerick, Limerick, Ireland 5. Health Research Institute UL, UL Hospitals Clinical Research Unit (CRU), University of Limerick, Limerick, Ireland
Regular physical activity is important for people with rheumatoid arthritis (RA). Sleep requirements for adults should be on a ‘sleep needs spectrum’ of between 7 to 9 hours per day. Poor sleep is a common complaint among people with RA, which may have an effect on their activity levels and well-being. There is a lack of objective information regarding total sleep time (TST) and its relationship with physical activity and disease related variables in people with RA.
Aim was to objectively measure sleep and energy expenditure in people with RA and to determine if relationships exist between sleep, physical activity and disease related variables among people with RA. There is evidence that physical activity and exercise can impact sleep quality and disturbances in other chronic disease populations therefore, examining how they could affect sleep in RA is important.
A cross-sectional study design was used to recruit people with RA attending rheumatology outpatient clinics. Participants had to have a confirmed diagnosis of RA according to the American College of Rheumatology (ACR) classification criteria. A SenseWear(R)TM armband was applied to the right upper arm and participants were encouraged to wear same for 24 hours a day for 8 days. Subjects were contacted 3 times during the week to remind them to continue to wear the monitor. Four valid days with 95% wear time was determined as the measurement criteria.
Seventy five participants completed the required period of monitoring, with 32 subjects having the required wear time. The mean TST was 5.7 (SD 1.11) hours per night, with a median 1.25 (IQR 1.88) hours of daily physical activity. Sleep time had a positive significant relationship with physical activity (p=0.018); physical activity also demonstrated a negative significant relationship with functional limitation (p=0.009); physical activity energy expenditure further demonstrated a significant negative correlation with disease activity (p=0.011) and low disease activity was strongly correlated with improved global health (p<0.001). Therefore, those who were more active had the longest TST, with reduced functional limitations. Those who expended more energy had lower disease activity with improved global health. Physical activity correlated with lower CRP levels and CRP levels had in turn a significant relationship to global health (p=0.034).
This study has demonstrated that people with RA who are more physically active have longer TST. Disease related and functional variables also correlate with sleep, with lower CRP, lower DAS, lower HAQ and increased global health in those with higher physical activity levels and longer TST. These findings are significant given recent information that sleep is commonly reduced in people with RA and that people with RA have lower physical activity profiles.
People with RA have varied sleep patterns and fall below the required ‘sleep needs spectrum’. Future research should specifically investigate the effect of physical activity and exercise on sleep and from this, the most effective exercise prescription in terms of the FITT principle and, the ideal approach to exercise delivery and how compliance can be promoted.