Aim: To assess anxiety-like behavior in rats after twelve hours of sleep fragmentation during the light phase of sleep-wake cycle, using the elevated plus maze test.
Introduction: Hallmark of sleep fragmentation is set of frequent, brief arousals, which modulates sleep architecture without significant diminishment of total sleep time. Anxiety is recognized as comorbidity in numerous disorders, including some of those related to sleep quality. Sleep fragmentation may be appropriate model of sleep alteration pattern in some disorders, yet its effects on behavioral alterations have not been broadly investigated.
Methods: Sleep fragmentation was achieved by treadmill method lasting for 12h, during the light phase of the day (starting at 8AM). Wistar albino male rats were randomly divided into: sleep fragmentation group (SF, n=8, treadmill programmed to alternately work 30s ON and 90s OFF every 2min); activity group (AC, n=8, treadmill programmed to alternately work 10min ON and 30min OFF); and treadmill control group (TC, n=8, rats stayed in the treadmill set to OFF mode and conditions equivalent to cages). Immediately after the sleep fragmentation regimen, elevated plus maze test was performed. To assess anxiety-like behavior, we measured time spent in the open arms, as well as number of transitions between open and closed arms.
Results: SF group spent significantly less time in the open arms compared to both, AC and TC group (p<0.001). SF rats also had significantly less number of transitions between closed and open arms of the maze, compared to AC and TC group (p<0.05). Moreover, no significant difference was observed in any of the measured parameters between TC and AC group.
Conclusion: The results of our study indicate that acute 12-h sleep fragmentation induced anxiety-like behavior in rats in elevated plus maze. Further research should help us better understand impact of this phenomenon on psychiatric disorders.