The more frequent and severe the insomnia, the greater the sensitivity to pain, the Norwegian study showed. Additionally, the researchers noted that people with insomnia who also suffer from chronic pain have an even lower threshold for physical discomfort.
The study, led by Borge Sivertsen, of the Norwegian Institute of Public Health in Bergen, involved more than 10,000 adults. The study participants all underwent a standard test of pain sensitivity by dunking their hands in a bath of cold water for 106 seconds.
The volunteers were also asked about their sleep quality. The researchers also took into account other factors that might affect pain tolerance, such as recurring pain, depression and anxiety.
They found that nearly one-third of participants were able to keep their hand in the cold water for the entire test.
Those with insomnia, however, were more likely to remove their hand from the water early. In fact 42% of people with insomnia pulled their hand out before the test ended, compared to 31% of those without this sleep disorder, the study published in the journal PAIN revealed.
People with more severe cases of insomnia had greater pain sensitivity, suggesting tolerance of pain drops along with sleep quality. People with insomnia and chronic pain were more than twice as likely to have reduced tolerance to pain, the research revealed.
