Strength of the 24-hour component in the activity spectrum, an objective measure of rhythm robustness from periodogram or cosinor analysis.
Use circadian spectral power to compare rhythm strength objectively across animals or treatments. The activity time series is decomposed by FFT, Lomb-Scargle, or chi-square periodogram, and the power at the ~24 h period is read off as the rhythm strength. A tall 24 h peak means a strong clock; a flat spectrum means disruption.
| Primary value | Power (height) of the spectral peak at the circadian period |
|---|---|
| Common units | Spectral power, arbitrary units; or percent rhythm |
| Compatible assays | Home-cage video, wheel, beam-break, telemetry |
| Required boundary | Spectral method, record length, and detrending |
| Do not infer alone | Phase or the direction of any period change |
Bin the activity record, detrend it, and apply FFT, the Lomb-Scargle periodogram (preferred for gappy or unevenly sampled data), or the chi-square periodogram. Report the power at the dominant circadian peak. Cosinor fitting gives an equivalent parametric amplitude and goodness of fit.
Spectral power scales with overall activity and record length, so it is a relative measure best compared within a study under matched conditions. A reduced 24 h peak signals a weaker rhythm but does not say whether the clock is slow, fragmented, or mistimed.
Store animal ID, spectral method and parameters, record length, detrending, peak period, peak power, and lighting condition.
Endpoint pages should cite the method literature behind the scored value and keep high-specificity protocol claims qualified unless the source supports them.
Endpoint articles link to adjacent products, software workflows, and sibling endpoints where the connection is useful and already routable.
