Circadian rhythms and nursing research: methodological considerations.

The role circadian rhythms play in mental health, sleep, human development and aging, pharmacologic efficacy, immune function, and cardiovascular health makes them a natural focus of nursing research. Integration of chronobiologic concepts into nursing care demands sound empirical support. Nevertheless, issues such as detection of linear trends, the fit of circadian data to a cosinor model and circular distributions, add complexity to the collection, analysis and interpretation of circadian rhythm data. The purpose of this paper is to convey an informed understanding of ways in which to deal with this intricate assembly of issues.