Continuity of sleep, not just the total hours of nightly slumber, is crucial to forming and retaining memories, a new study in mice suggests.

Mice couldn’t remember objects they’d seen before after a night of interrupted sleep, Asya Rolls of Stanford and her colleagues report online July 25 in the Proceedings of the National Academy of Sciences. Even though the mice got just as much sleep as normal and slept as intensely as usual, breaking that sleep into one-minute chunks was enough to erase the memory of toys the animal had seen before.

The results emphasize that sleep is a process, says Paul Shaw, a neuroscientist at Washington University in St. Louis who was not involved in the study. “Whatever biological function sleep serves takes time,” he says. “So if you wake up, you disrupt that process and have to start from scratch again.”

via Tossing, Turning, Forgetting – Science News.