spectr provides a consistent interface to use various methods to calculate the periodogram and estimate the period of a rhythmic time-course. Methods include Lomb-Scargle, fast Fourier transform, and three versions of the chi-square periodogram.

Optogenetic stimulation of VIPergic SCN neurons induces photoperiodic-like changes in the mammalian circadian clock, Tackenberg et al., Eur J Neurosci 2021

The risks of using the chi-square periodogram to estimate the period of biological rhythms, Tackenberg and Hughey, PLOS Comput Biol 2021