"This study finds that fragmented sleep profiles, akin to individuals suffering from middle of the night insomnia, health care workers on call, and parents caring for infants, alter natural systems that regulate and control pain, and can lead to spontaneous painful symptoms," says researcher Michael T. Smith, Ph.D., of Johns Hopkins University, in a news release.
Researchers say the results suggest that frequent sleep disturbances, not just sleep deprivation, may affect how women perceive pain and play a role in chronic pain conditions.
In the study, published in Sleep, researchers controlled the sleeping patterns of 32 healthy women for seven nights and compared their pain symptoms.
All the women slept undisturbed in a sleep lab for the first two nights. Then the women were divided into three groups for the nights three through five. The first group slept undisturbed for eight hours, the second group was awakened once an hour for eight hours, and the third group was sleep deprived with a delayed bedtime. On the last two nights, both the disturbed sleep group and the sleep-deprived group were deprived of sleep for 36 hours followed by an 11-hour recovery sleep.
Throughout the study, researchers assessed the women's pain thresholds and pain inhibition.
The results showed that only the women in the disturbed sleep group experienced an increase in spontaneous pain and decrease in pain inhibition.
"Our research shows that disrupted sleep, marked by multiple prolonged awakenings, impairs natural pain control mechanisms that are thought to play a key role in the development, maintenance, and exacerbation of chronic pain," Smith says.
By Jennifer Warner
Reviewed by Louise Chang, M.D.
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