USE OF A SPREADSHEET PROGRAM FOR CIRCADIAN ANALYSIS OF BIOLOGICAL PHYSIOLOGICAL DATA/

Biological/physiological data sampled over a period of 24 h can be sub jected to a mathematical analysis to determine the presence of circadi an rhythmicity. Several procedures have been proposed, most being comp lex. To render such an analysis simpler and easy to use by non-mathema ticians, we developed and tested the cosinor technique using a commonl y available commercial spreadsheet (Excel(R)). It can be used to analy ze equally or unequally time-spaced data over 24 h with missing data, as well as to calculate the significance and the main limit of the res ultant circadian rhythm (mesor, amplitude, acrophase and their confide nce limits). Examples of its application to hourly samples of plasma c ortisol and minute-by-minute rectal temperatures are shown.