Distribution of sleep structure is maintained, but adjusted in an acute circadian shift: a study by continuous long-term local field potential recording

Abstract

Evidence suggests that the disruption of circadian rhythms has a negative impact on memory retention. It is therefore speculated that circadian disruption influences some property of sleep responsible for memory retention, but little is known about this relationship. In order to investigate this question, we have continuously recorded local field potentials in the hippocampus and prefrontal cortex of freely behaving adult male Long Evans rats. The current analysis indicates that daily quantities of sleep are strongly maintained in an acute circadian shift. Furthermore, hourly sleep distributions are largely maintained during the shift. Contrastingly, an acute circadian shift is able to alter the hourly distribution of vigilance states and sleep based events predominantly across pre-entrainment to post-entrainment, supporting previous findings of memory retention deficits observed during post-entrainment but not shifting epochs. Furthermore, current analysis suggests that pre-entrainment hourly distributions are conserved, but relocated in phase with post-entrainment.