Comparison of the sleep pattern throughout a protocol of chronic sleep restriction induced by two methods of paradoxical sleep deprivation

The purpose of the present study was to evaluate the sleep homeostasis of rats submitted to a protocol of chronic sleep restriction by two methods and to evaluate the sleep characteristics during the recovery period. The sleep restriction protocol was accomplished by sleep depriving rats for 18 h everyday for 21 days, using the single platform method (SPM) or the modified multiple platform method (MMPM) of paradoxical sleep (PS) deprivation. Rats were allowed to sleep for 6 h (from 10:00 to 16:00; starting 3 h after lights on) in their individual home-cages, during which their sleep was recorded. At the end of the sleep restriction protocol, rats were recorded in their home-cages for 4 days, where they could sleep freely. Both methods used to induce chronic sleep restriction were effective, in sofar as they resulted in augmented sleep time during the 6 h-sleep period, with very few bouts of wakening. Although comparison between the methods did not reveal differences, sleep restriction under MMPM produced a more consistent daily rebound, mainly of paradoxical sleep, with longer episodes. These results showed distinct sleep recovery patterns, suggesting a possible role of the waking experiences (i.e. immobilization stress, social interaction) acting on sleep consolidation.