Sleeping in the wrong position or on a lumpy mattress are rarely the reasons you may wake up feeling more pain than the night before. In fact, the body’s biological “circadian” clocks — the internal factors that govern wake-sleep cycles — are the reason for morning pain.

That’s the upshot of new research by the University of Manchester that suggests that sleep helps restore our bodies by suppressing inflammation — a key source of pain — but that it comes flooding back once we wake in the morning.

Lead researcher Julie Gibbs and her colleagues suggest the study may help explain why the 1.5 million Americans with rheumatoid arthritis and other inflammatory diseases find it especially difficult to get out of bed in the morning because of painful joints.

Her findings — published in the FASEB Journal, published by the Federation of American Societies for Experimental Biology — may also lead to new ways to treat chronic pain naturally by modifying the wake-sleep cycle.

“There is strong [daily cycle] variation in the symptoms and severity of chronic inflammatory diseases, such as rheumatoid arthritis,” Gibbs concluded. “In addition, disruption of the circadian clock is an aggravating factor associated with a range of human inflammatory diseases.

“We conclude that under chronic inflammatory conditions, the clock actively represses inflammatory pathways during the dark [sleep] phase. This interaction has exciting potential as a therapeutic avenue for treatment of inflammatory disease.”

To reach their conclusions, Gibbs and her colleagues studied the cells of mice and people with rheumatoid arthritis to determine the role our inner body clocks — known as “circadian rhythms,” which regulate when to go to bed and when to get up — play in inflammation.

They found that mice exposed to constant light had more swelling in their limbs and inflammation markers in their blood. But during “dark phases,” the inflammation decreased — in part because of changes in “core clock proteins” involved in circadian rhythms that are linked to inflammation known as “cryptochromoes.”

The researchers suggested the findings point the way to additional studies that might lead medical investigators to develop new drugs and therapies to modify these proteins to ease pain.

Further research based on Gibbs’ findings may also help doctors determine whether taking pain medication at certain times of the day — right before going to bed, or immediately upon waking — would make them more effective.

In the meantime, the researchers suggest people with joint pain take steps to sure to get sufficient sleep every night —experts generally recommend seven to eight hours.

They also say it’s important to go to sleep and wake up at the same time every day, to establish and keep their bedrooms as dark as possible to establish a healthy wake-sleep cycle that suppresses information at night.