Modeling daily and subdaily cycles in rat sleep data

We developed a statistical model for rat sleep-wake behavior over the 24-ho ur day; this model could be used for animals exposed to shorter cycles of I ie:ht and dark conditions. Rat behavior was classified either as "wake" or "sleep," as determined by analysis of electrophysiological data. The propos ed model consists of three parts: the first two explain cyclic effects rela ting to the lighting conditions, whereas the last Dart reflects any acyclic effect. Hypothesis tests were conducted on the magnitude of the parts. The model also accounts for correlated errors.