“We know that pain affects the spouse’s emotional well being, and that over time it takes a toll on the relationship, but until now we did not know the extent to which pain affects spouse sleep,” said Lynn Martire, associate professor of human development and family studies, Penn State. “Getting adequate sleep is important for maintaining long-term health.”
The team recruited 138 patients with knee osteoarthritis and their spouses to complete baseline interviews plus daily diary entries for 22 days. To be eligible for the study, one member of each couple had to have been diagnosed with knee osteoarthritis by a physician, had to experience knee pain of moderate to great intensity and had to be at least 50 years old. The couples had to be married or in a long-term relationship in which they shared a residence.
Following the baseline interview, the researchers trained the participants to use handheld computers to answer questions about their daily pain and sleep quality.
“Very few studies on couples have the intensive, repeated measures design we used in which we asked people questions every day as opposed to just interviewing them at one or two time points,” Martire said.
The team’s results will appear in the Aug. 16 issue of the journal PAIN®.
“We found that greater knee pain was associated with spouses’ poorer sleep quality that night and feeling less refreshed after sleep,” Martire said. “We don’t yet know the mechanism by which a person’s pain affects his or her spouse’s sleep. In our study, we examined several possibilities, including disturbances in patient sleep and quality of marital interactions during the day, but did not find that these factors explained our findings.”
The team also found that patient pain was more strongly related to less refreshing sleep for spouses who both reported that they had a close relationship.
“We usually think of closeness as a good thing, but being overly involved in each other’s health could actually have some negative implications — it could take a toll on your health over time,” Martire said.
In the future, the researchers plan to investigate physiological changes, such as changes in heart rate variability, and neurological changes.
“There’s an interesting line of research showing that people have the same neurological response to witnessing pain in somebody they love as they have to being in pain themselves,” Martire said.
Other authors on the paper include Francis Keefe of Duke University, Richard Schulz of the University of Pittsburgh, Mary Ann Parris Stephens of Kent State University and Jacqueline Mogle of Penn State.
The National Institutes of Health supported this research.