A paradoxical impact of alcohol on sleep-memory coupling

Abstract

Sleep serves a fundamental role in memory consolidation, and yet it must adapt to the organisms physiological state. The latter is impacted profoundly by acute ethanol consumption, but whether intoxication affects the role of sleep in memory consolidation remains unexplored. Here, we demonstrate that acute ethanol inverts the canonical link between sleep and memory in Drosophila. Typically, satiated flies require sleep for appetitive memory consolidation, but starved flies that must forage for food switch to sleep-independent memory. Ethanol selectively impairs memory consolidation in satiated flies by causing a switch to sleep-independent memory, which then cant be supported because of ethanol-induced sedation. Under these conditions, sleep deprivation rescues memory and requires the upregulation of neuropeptide F, which signals through NPF receptors on PPL1 dopaminergic neurons. We suggest that reward-seeking behaviors, induced by starvation or ethanol, invoke sleep-independent memory. However, ethanol has a paradoxical impact, wherein it induces a switch in memory pathways but concurrently suppresses consolidation through the preferred pathway, thereby causing sleep to become detrimental for memory consolidation.