Veronica Hackethal, MD
December 09, 2019
Sleep problems may decrease the likelihood of recovery from chronic low back pain (LBP) over the long term and those who have musculoskeletal pain on top of insomnia have an even lower possibility of recovery, a study has found.
"The probability of recovery [from LBP] is especially low among persons who often/always experience sleeplessness and who also suffer from co-occurring musculoskeletal pain," the researchers write.
"Preventing or reducing sleep problems among people with chronic LBP may have the potential of improving the long-term prognosis," they add.
Eivind Schjelderup Skarpso, PhD, Norwegian University of Science and Technology, Trondheim, and colleagues with the HUNT study, published their findings online December 4 in the Journal of Epidemiology & Community Health.
The study took place over more than 10 years and also found the likelihood of recovery from chronic LBP decreased further among people with muscle and joint pains, in addition to sleeplessness.
The researchers conducted a prospective cohort study that included 3712 women and 2488 men aged at least 20 years who participated in the HUNT study, one of the largest, longest running health studies in Norway. HUNT began in 1984 and has data on over 120,000 participants.
The current study included participants who reported chronic LBP when they enrolled in the HUNT study in 1995 to 1997, with follow-up occurring at 2006 to 2008. Participants reported sleeplessness/insomnia and co-occurring musculoskeletal pain on questionnaires at baseline and reported chronic LBP pain at baseline and follow-up. Researchers adjusted analyses for age, body mass index, physical activity, education level, and smoking.
During approximately 11 years of follow-up, 40.6% (1508) of women and 52.1% (1296) of men recovered from chronic LBP.
Compared with people without sleeplessness, those who often or always experienced sleeplessness had lower probability of recovering from chronic LBP. This probability was lower in women compared with men (risk ratios [RR], 0.65 vs 0.81, respectively).
The probability of recovering from chronic LBP decreased as the number of insomnia symptoms increased. For example, women who reported one insomnia symptom had 19% lower likelihood of recovery compared with those who reported no symptoms (RR, 0.81). In women who experienced two and three insomnia symptoms, the likelihood of recovery was 32% lower and 40% lower, respectively (RRs, 0.68 and 0.60, respectively). The likelihood of recovery was 1%, 16%, and 18% lower among men who experienced one, two, and three insomnia symptoms (RRs, 0.99, 0.84, and 0.82, respectively).
The probability of recovery also decreased with increasing musculoskeletal pain at other locations in the body. Among participants without sleep problems, women with musculoskeletal pain at five or more body sites had a 46% lower likelihood of recovery (RR, 0.54) compared with women with no co-occurring musculoskeletal pain. Men with corresponding symptoms had a 31% lower likelihood of recovery (RR, 0.69) compared with those without co-occurring musculoskeletal pain.
The likelihood of recovery decreased even more when musculoskeletal pain accompanied sleep problems. Participants who often or always had sleep problems accompanied by musculoskeletal pain at five or more sites in the body had the lowest likelihood of recovery (women: RR, 0.40; men: RR, 0.59).
LBP represents the leading cause of years lived with disability worldwide. Sleep problems often go along with LBP and have been linked to increased pain intensity as well as persistence of pain. The mechanism remains unknown; however, some studies have suggested that poor sleep may increase inflammation in the body and change how the brain processes pain.
Often, pain in muscles and other joints accompany LBP and, again, the impact of insomnia and musculoskeletal pain on long-term recovery are not well understood.
The reasons for the lower likelihood of recovery among women compared with men may be a result of chance or could be related to sex differences in how sleep affects processing of pain in the brain, the researchers explain.
Study limitations include the fact that assessment of sleeplessness did not fulfill criteria for a diagnosis of insomnia, according to International Classification of Sleep Disorders (ICSD-3) criteria. In addition, the researchers could not assess changes over time in sleeplessness, insomnia, and co-occurring musculoskeletal pain, so they were unable to evaluate whether improvement or worsening in these factors affects recovery from LBP.
The study was supported by grants from the Liaison Committee between the Central Norway Regional Health Authority (RHA) and the Norwegian University of Science and Technology (NTNU), and from The Norwegian Fund for Post-Graduate Training in Physiotherapy. The authors have disclosed no relevant financial relationships.