A new study shows that sleeping soon after learning new material is best for recall.
Notre Dame psychologist Jessica Payne and colleagues studied 207 students who habitually slept for at least six hours each night. Participants were randomly assigned to study declarative, semantically related or unrelated word pairs at 9 a.m. or 9 p.m., and returned for testing 30 minutes, 12 hours or 24 hours later.
Declarative memory refers to the ability to consciously remember facts and events. It can be broken down into memory for events — known as episodic memory — and semantic memory, which is memory for facts about the world.
People routinely use both types of memory every day, such as recalling where we parked or learning how a colleague prefers to be addressed, Payne said.
At the 12-hour retest, memory was superior following a night of sleep compared to a day of wakefulness, she said.
However, this performance difference was a result of a pronounced deterioration in memory for unrelated word pairs, she said, noting there was no difference for related word pairs. At the 24-hour retest, with all subjects having received both a full night of sleep and a full day of wakefulness, memories were superior when sleep occurred shortly after learning, rather than following a full day of wakefulness.
“Our study confirms that sleeping directly after learning something new is beneficial for memory,” she said. “What’s novel about this study is that we tried to shine light on sleep’s influence on both types of declarative memory by studying semantically unrelated and related word pairs.”
“Since we found that sleeping soon after learning benefited both types of memory, this means that it would be a good thing to rehearse any information you need to remember just prior to going to bed,” she continued. “In some sense, you may be ‘telling’ the sleeping brain what to consolidate.”
Titled “Memory for Semantically Related and Unrelated Declarative Information: The Benefit of Sleep, the Cost of Wake,” the study was published March 22 in PLOS One.
Source: University of Notre Dame