TEMPORAL DISTRIBUTION OF THE SLEEP-WAKE C YCLE PHASES IN THE CAT - 23HRS REGISTER IN LIGHT-DARKNESS AND DARKNESS-LIGHT CONDITIONS

The cat can be profitably used for chronobiological studies of sleep-w akefulness and other physiological circadian rhythms. Four stages of t he sleep-wakefulness cycle have been described In this animal Wakefuln ess (W). Slow Wave Sleep I (SWS I) Slow Wave Sleep II (SWS II) and Rap id Eyes Movement Sleep (REM) Convincing sleep-wakefulness rhythms had not previously been well-established for this animal mainly regarding environmental Indicators as the light-dark cycles. The purpose of this study was to identify and to describe the temporal distribution of th e sleep-wakefulness cycle in the cat an 23 hours recording under Light -Dark (L-D) 12:12 hours and Dark-Light (D-L) 12:12 hours conditions. E ight freely-moving adult male cats chronically implanted for conventio nal sleep recording were studied. All animals underwent 23 hour sleep recordings twice a week starting at 8:30 am. Four cats were recorded i n D-L and four in L-D cycle, a total 50 recordings were obtained. The following variables were analyzed, sleep stages number (NF), duration percentage (%), duration average ((x) over bar) and total time (TT) of each hour. Periods from 0-12 hours and from 12-23 hours were analyzed under light and dark conditions, Results showed that the sleep total time predominates in the 0-12 hours periods. Significant differences d id not appear between light and dark periods regarding NF, %, (x) over bar and TT in all stags. Aumented REM sleep % under the light period of the L-D cycle was an exception. Temporal distribution of SWS I and SWS II did not show significant differences in the hour by hour analys es The REM sleep ocurrence had inverse relation with W stage. The resu lts show that the REM sleep ocurrence is related to the W decrease The sleep-wakefulness cycle In the cat is not strictly related to light a nd dark periods, nevertheless is reinforced in L-D cycle.