Memory’s 24-Hour Sweet Spot Suggests Daily Review Boosts Recall

New research using sea slugs (Aplysia) finds that a second exposure to a learning stimulus exactly 24 hours after the first activates a molecular mechanism that boosts long-term memory; shorter or longer intervals fail to trigger it. By mimicking learning in a controlled cell-plating setup, scientists observed a timer-like process—likely involving CREB1/CREB2—that primes memory when reviews occur at the same time the next day. The findings support spaced repetition over cramming and suggest a universal cellular clock for memory across species, though further work in higher animals is needed.