A general decline in both the quantity and quality of hours slept led to a two- to three-fold increase in pain problems over time, researchers found.

“Sleep and pain problems are two of the biggest health problems in today’s society,” said lead study author Esther Afolalu of the University of Warwick in Coventry.

Pain is known to interfere with sleep, she told Reuters Health by email. But the new study shows “that the impact of sleep on pain is often bigger than (the impact of) pain on sleep,” she said.

Sleep disturbances, she added, contribute to problems in the ability to process and cope with pain.

Afolalu and colleagues reviewed 16 studies involving more than 60,000 adults from 10 countries. The studies looked at how well people were sleeping at the start, and then evaluated the effects of long-term sleep changes on pain, immune function and physical health. Half the participants were tracked for at least four and a half years.

Overall, sleep reductions led to impaired responses to bacteria, viruses and other foreign substances, more inflammation, higher levels of the stress hormone cortisol and other biomarkers related to pain, fatigue and poor health. Newly developed insomnia doubled the risk of a chronic pain disorder and hip fracture problems, the study authors wrote in the journal Sleep Medicine.

Deterioration in sleep was also associated with worse self-reported physical functioning.

At the same time, researchers didn’t find links between increased sleep and less pain or arthritis, although they did find that improvement in sleep was associated with better physical functioning.

One limitation of the analysis is that the studies relied on participants to recall their own sleep patterns. Also, the studies didn’t all use the same tools to measure sleep quality and quantity.

Future studies should look at sleep patterns for different groups of people and how that affects health, Afolalu said. Her team is now analyzing data from the UK Household Longitudinal Survey to understand sleep, insomnia and health for people with arthritis.

Additional studies should also investigate how sleep deficiency leads to chronic pain disorders, said Dr. Monika Haack, who studies sleep, pain and inflammation at Harvard Medical School’s Human Sleep and Inflammatory Systems Lab in Boston.

Haack, who wasn’t involved with the new research, said in an email, “It is also important to identify whether there is a specific sleep pattern that is most dangerous for pain. For example, does sleep disruption (with frequent, intermittent awakening throughout the night) have a higher impact than a short but consolidated sleep?”

Haack and colleagues recently reported in the journal Pain that restricting sleep on weekdays and catching up on the weekends led to more pain. Furthermore, people who caught up on weekends had a tougher time dealing with pain than those who slept eight hours every night.

“In those already suffering from chronic pain, it is of critical importance to incorporate sleep improvement strategies,” Haack said. “And to have sleep specialists as part of the pain management team.”