Increased Insomnia Symptoms Predict the Onset of Back Pain among Employed Adults

BACKGROUND Back pain is among the most prevalent pain disorders causing chronic disability among adults, and insomnia is a common co-morbidity. However, whether insomnia precedes back pain or vice versa remains unclear. The current study tested the temporal association between insomnia and back pain. METHODS A longitudinal design was used to investigate whether changes in insomnia over time predict the onset of back pain and vice versa. The study was conducted on a cohort of active healthy working adults (N = 2,131, 34% women) at three time points (T1, T2, and T3) over a period of 3.7 years (range = 2.2-5.12) years. Logistic regression analysis was used to test whether increased insomnia symptoms from T1 to T2 predicted the onset of new back pain. Ordinary least squares regression was used to test whether the existence of back pain at T2 predicted an increase in insomnia from T2 to T3. RESULTS The results indicated that after controlling for socioeconomic variables, self-reported health, lifestyle behaviors, and anthropometrics, a T1-T2 increase in insomnia symptoms was associated with a 1.40-fold increased risk of back pain at T3 (OR = 1.40; 95% CI = 1.10-1.71). No support was found for reverse causation; i.e., that back pain predicts subsequent increase in insomnia. CONCLUSIONS Insomnia appears to be a risk factor in the development of back pain in healthy individuals. However, no evidence of reverse causation was found.