More night than day--circadian rhythms in polymyalgia rheumatica and ankylosing spondylitis.

The circadian rhythm of symptoms in patients with chronic inflammatory diseases is well known. Circadian rhythms could be used to identify targets for time-adapted antiinflammatory therapies, which are administered prior to the flare of cytokine synthesis and inflammatory activity. In recent years, the diurnal variations in rheumatoid arthritis have been described precisely for pain, stiffness, and functional disability, as well as the underlying cyclic variations in hormone levels and cytokine concentrations. This review summarizes the current knowledge on circadian rhythms in other rheumatic diseases, focusing on polymyalgia rheumatica and ankylosing spondylitis.