By Pat Anson, Editor

A new study is adding to the growing body of evidence linking poor sleep habits to chronic pain.

Researchers at Johns Hopkins University School of Medicine say patients with knee osteoarthritis (OA) who slept poorly had greater central sensitization -- which amplifies the amount of pain they feel. They are also more likely to catastrophize -- a clinical term meaning they were consumed by thoughts about pain.

Osteoarthritis is a joint disorder that leads to thinning of cartilage and progressive joint damage. Nearly 40 percent of Americans over the age of 45 have some degree of knee OA.

"Our study is the largest and most comprehensive examination of the relationship between sleep disturbance, catastrophizing and central sensitization in knee OA," said lead author Claudia Campbell, PhD, from the Department of Psychiatry & Behavioral Sciences at Johns Hopkins University School of Medicine. The study is published in Arthritis Care & Research.

The study included 208 participants who were categorized into four groups: OA patients with insomnia, OA patients with normal sleep habits, healthy controls with insomnia, and healthy controls without pain and normal sleep habits. Most of the participants were female.

Results showed that patients with knee OA and insomnia had the greatest degree of central pain sensitization compared to the controls. Researchers also found that patients with poor sleep and high catastrophizing scores reported higher levels of central sensitization -- which was associated with increased  pain.

"While no causal processes may be determined from this study, our data suggest that those with low sleep efficiency and higher catastrophizing have the greatest central sensitization. Understanding the intricate relationship between sleep, central sensitization, and catastrophizing has important clinical implications for treating those with chronic pain conditions such as knee OA," said Campbell.

A recent study in Norway found that getting a good night’s sleep plays a key role in determining how bad your pain levels are doing the day.  Those who had trouble sleeping at least once a week had a 52% lower pain tolerance. The study, which was published in the journal PAIN,  is the first to link insomnia and impaired sleep to reduced pain tolerance in a large, general population sample.  

A previous study in Norway found that women who have trouble sleeping are at greater risk of developing fibromyalgia.