Among participants with insomnia, those who also had knee osteoarthritis reported more sleep interruptions and had less “sleep efficiency,” the authors report in the journal Arthritis Care and Research.
Sleep efficiency is determined by how much time you spend asleep after you go to bed and turn the lights off.
Researchers also measured signs of what’s known as central sensitization, a nervous system condition linked to long-term exposure to chronic pain that makes people have a lower pain threshold.
Patients with knee osteoarthritis and insomnia were most sensitive to pain, based on assessments of central sensitization, the study found.
While sleep patterns have long been linked to pain perception, the study sheds new light on how insomnia transforms pain perception through central sensitization in people with knee osteoarthritis, said Dr. Gillian Hawker, a researcher in musculoskeletal diseases at the University of Toronto who wasn’t involved in the study.
But the study can’t prove that insomnia causes pain, because it’s hard to say which problem developed first, Hawker said by email.
“People with a lot of joint pain have difficulty sleeping, which can result in greater fatigue and depressed mood and pain severity,” Hawker said. “Physical activity, which is the primary therapy for knee osteoarthritis, helps sleep, pain, mood and functioning.”