Estimating Circadian Sleep/Wake Cycle From Rest/Activity Behaviors In Inbred Strains Of Rats

To establish methods to screen inbred rat strains, we studied EEG/EMG and movement in Brown Norway (BN MCWi ), Fawn Hooded (FH MCWi ), and Dahl Salt Sensitive (SS MCWi ) inbred rat strains in environmental chambers during 3 successive 12L:12D circadian light:dark cycles. The 3 rd light:dark cycle was analyzed for the circadian relationship of the onset, offset and duration of sleep state and movement. Although circadian amplitude and phase onset of sleep was different* between strains, onset, offset and duration of sleep and movement were significantly* correlated within strains. Analyzing probability of sleep onset and sleep offset from duration of inactivity we established a 95% probability* of sleep after 35 sec and 0.75 sec, respectively, that was NOT different* within and between strains. We developed an algorithm to determine sleep/wake periods from movement in previously unstudied FH MCWi and BN MCWi rats and found we correctly* estimated sleep onset (90%) and sleep offset (96%) in all observations. We have revised the algorithm to estimate 4 periods of sleep/wake (Active Wake, Quiet Wake, Sleep and Sustained Sleep) to further characterize sleep/wake. In conclusion we have established methods to screen sleep/wake patterns in consomic, congenic and ENU mutated inbred rat strains and to investigate physiological dysfunction and sleep in these models. This study was funded by NHLBI (U01 HL66579) (*P < 0.05)