A novel experimental design to avoid rem sleep rebound

Introduction Several studies report about the phenomenon of REM sleep rebound which is occurred after cessation of deprivation of this sleep stage conducted by various instrumental techniques. According to our previous works REM sleep replacement by waking episodes does not lead to accumulation of REM sleep need. On the basis of this statement we have elaborated special experimental scheme of to avoid REM sleep rebound appearance. Here we present the results of these experiments. Materials and methods Eight mature cats weighing 2.8–3.5 kg were implanted with electrodes for standard sleep-wake cycle (SWC) recordings. After establishment of baseline SWC REM sleep deprivation was performed using classic method of short-term awakenings using MRF stimulation during eight hours. Then, the four animals (experimental (E)) were not allowed to fall asleep through the maintenance of active waking state during one hour by using electrical stimulation of the posterior hypothalamus; this procedure was followed by the six- hour post-deprivation period. Another four cats (control (C)) could realize SWC without any interventions. Duration of individual episodes of different SWC phases/stages, their total amount and percent ratio were calculated and compared with corresponding baseline data. Results As it was expected, REM sleep propensity increased during deprivation hours with frequent enforced awakenings from this stage, and REM sleep rebound was occurred in the C - group animals with significant decrease of REM sleep latency. However, in E- cats, either total REM sleep amount or the time needed for the transitions of slow- wave sleep to REM sleep did not differ from baseline. No increase of ponto- geniculo-occipital waves or rapid-eye- movements was found in the episodes of E-cat’s REM sleep while the frequency of these indices increased significantly in the C-group. Conclusion Results provide additional support for our opinion that active waking state is able to satisfy the inner need for REM sleep even in the conditions of substantial increases in the REM sleep propensity and prevents the occurrence of REM sleep rebound. Acknowledgement We are very thankful to Prof. Tengiz Oniani who was supervisor of the present study.