Abstract: Objective: To observe the influence of heterogeneity on sleep-wake architecture in single-prolonged stress (SPS) animal model. Methods: SPS rats were subdivided into low responders (LR) and high responders (HR) based on their freezing responses to a novel environment. Sleeping time (ST), awakening numbers (AN), brief awakening numbers (bAN) and frequency distribution of sleep bouts were used as observing indicators, single factor variance analysis combined with Dunnett t test were used to compare the differences between control, exposure, LR and HR groups. Results: We found sleeping time was increased only in HR group. Moreover, awakening numbers and brief awakening number increased in exposure group and HR group during the light phase, but not in LR group. The number of sleep bouts for the ranges of 40-80s increased obviously in HR group, but not in exposure and LR group. In addition, there were significant correlation between sleep-related parameters and freezing in HR group, but not in LR group. Conclusion: Heterogeneity existed in SPS model in view of different sleep-wake architectures of SPS rats. Rats in HR group exactly mimicked the freezing response and sleep disorders of PTSD. So HR rats were more appropriate to be used as PTSD-like models, especially when studying sleep disorder in PTSD.

Key words: sleep-wake architecture, heterogeneity, single prolonged stress