Revealed: Why your body feels stiff after you wake up in the morning

Researchers have found that a protein created by the body's "biological clock" regulates inflammatory arthritis, explaining why the human body is often found to be stiff in the morning hours.

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The findings showed that the protein, called CRYPTOCHROME, represses inflammatory pathways within the affected limbs during nighttime sleep, making inflammation symptoms, such as stiffness, seem worse when this effect wears off as one wakes up.

Disruption of the circadian clock has been an aggravating factor associated with a range of human inflammatory diseases, such as rheumatoid arthritis, said the paper.

"By understanding how the biological clock regulates inflammation, we can begin to develop new treatments, which might exploit this knowledge," said Julie Gibbs, Lecturer at the University of Manchester, in Britain.

"Furthermore, by adapting the time of day at which current drug therapies are administered, we may be able to make them more effective," Gibbs added.

For the study, the team harvested cells from joint tissue of healthy mice and/or humans.

These cells, called "fibroblast-like synoviocytes," are important in the pathology that underlies inflammatory arthritis.

Each of these cells was found to keep a 24-hour rhythm, and when this rhythm was disrupted by knocking out the cryptochrome gene there was an increased inflammatory response.

This suggests that the cryptochrome gene product, the CRYPTOCHROME protein, has significant anti-inflammatory effects, the researchers noted.

Further, when the team administered drugs designed to activate the protein, protection against inflammation could be achieved.

The protein presents new opportunities for the development of drugs that may be used to treat inflammatory diseases and conditions, such as arthritis, the authors said.

The results appear in the The FASEB Journal.