Rats exposed to chronic alcohol display protracted insomnia and daytime sleepiness-like behavior during alcohol withdrawal✰.

ABSTRACT

INTRODUCTION: Alcohol use disorder (AUD), a chronic brain disorder, is characterized by a multitude of symptoms, including insomnia, during withdrawal. Previously, we have shown that rats exposed to chronic alcohol displayed insomnia-like symptoms during acute withdrawal. Since insomnia lasts for several years and is a major risk factor of relapse to alcoholism, the present study is designed to investigate the long-term effects of alcohol withdrawal on sleep-wakefulness. METHODS: Adult male Sprague-Dawley rats, instrumented with sleep recording electrodes, were divided into two groups Alcohol and Control. Rats were either administered alcohol (35% v/v), mixed with infant formula (Alcohol group) or control mixture containing water and infant formula (Controls; 10 mL/kg) every 8 h for 4 days using Majchrowicz's chronic binge drinking protocol. Electrographic recordings of sleep-wakefulness were performed until withdrawal day 7, however, the data was analyzed for withdrawal days 3, 5 and 7 in both Control and Alcohol groups. RESULTS: As compared to the controls, alcohol-exposed rats displayed insomnia-like symptoms as revealed by a) significant reduction in the quantity and quality of sleep during the light (inactive) period and b) a significant increase in NREM sleep with a concomitant reduction in the amount of time spent in the wakefulness during the dark (active) period of alcohol withdrawal. CONCLUSION: Our results suggest that the chronic binge model of alcohol dependence mimics clinical symptoms of AUD especially protracted insomnia and is suitable for understanding the mechanisms associated with alcohol withdrawal-induced behaviors.