Total Sleep Deprivation Modulates Working Memory and Depression in Aged Rats

Sleep deprivation has shown promise in rapidly alleviating depression symptoms without adverse effects, its impact on memory remains unclear, especially in depressed individuals. The study investigates the effects of total sleep deprivation on depression symptomatology and memory in aged rats with induced depression. The experiments were carried out on 8 adult male Sprague Dawley rats. A depression model was induced using the chronic retention stress paradigm. Total Sleep Deprivation was achieved using the gentle handling procedure. Behavioral tests, including the open field test, Y-maze, and novel object recognition test, were conducted to assess locomotor activity, spatial working memory, object recognition memory and depressive symptomatology. Sleep deprivation resulted in an initial increase in locomotor activity and exploration behaviors across different experimental setups. This heightened activity tended to normalize over time, suggesting a transient response to the lack of sleep. However, the total time spent in these zones was not significantly different from controls, suggesting that the fundamental engagement with the environment might remain intact despite altered entry behaviors. This suggests that the cognitive components of these behaviors may be resilient to short-term sleep loss. Overall, these findings suggest that the role of sleep is facilitating rather than essential in memory.