Example of activity cycle parameters derived from the extended Cosinor analysis.

<p>Each point represents a recording of activity intensity at a given time and the full line represents the fitted extended Cosinor curve. Nonlinear least-squares regression was used to fit actigraphy datasets to the model. The abscissa denotes time and the ordinate indicates activity intensity. Amplitude: difference between the peak and trough) of the fitted curve. Acrophase: time when the activity cycle reaches peak value. α: relative width of the curve at the middle of the peak. β: indicator of the steepness of the rise and fall of the curve. The coefficient of determination (or R²; not illustrated here), a measure reflecting the goodness of fit, was used as an indicator of circadian rhythmicity.