People suffering from insomnia and other sleep problems have increased sensitivity to pain, a new research, involving over 10,000 adults, has found.
The study underscores the need for efforts to improve sleep among patients with chronic pain and vice versa.
The results suggest that psychological factors may contribute to the relationship between sleep problems and pain, but they do not fully explain it.
"While there is clearly a strong relationship between pain and sleep, such that insomnia increases both the likelihood and severity of clinical pain, it is not clear exactly why this is the case," said lead researcher Borge Sivertsen from the Norwegian Institute of Public Health, Bergen.
The study included more than 10,400 adults from a large, ongoing Norwegian health study. Each participant underwent a standard test of pain sensitivity -- the cold pressor test -- in which the participants were asked to keep their hand submerged in a cold water bath.
Overall, 32 percent of participants were able to keep their hand in the cold water throughout the 106-second test.
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Participants with insomnia were more likely to take their hand out early: 42 percent did so, compared with 31 percent of those without insomnia.
Pain sensitivity increased with both the frequency and severity of insomnia.
Pain sensitivity was also linked to sleep latency, the amount of time it takes to fall asleep, although not to total sleep time.
The study was published in the journal Pain.