Verbal cues while asleep can boost the memory, at least when it comes to trying to learn new vocabulary and only when you grab a nap right after study time.

A new study reveals that it may be easiest to learn that second language if you incorporate some verbal cuing during a snooze right after studying.

The study relates memory retention is stronger for those who study vocabulary, then use a verbal cue, such as a tape that recites the same vocabulary, during sleeping. The key is the studying has to be within short order of the nap learning time.

"Reactivating memories during sleep by re-exposure to associated memory cues (e.g., odors or sounds) improves memory consolidation," states the study abstract.

The researchers, from Zurich and Fribourg universities in Germany, took a group of 60 German-speaking people and targeted the effort of learning Dutch words. Those who were re-exposed to verbal recitation of the words during sleep show greater memory retention on testing after the nap.

The entire group was asked to study the vocabulary at 10 p.m. Then one subgroup went to sleep listening to a recorded playback of the words, while the other group listened to the playback while awake.

At  2 a.m. all participants were then tested and the sleeping group beat out the other group.

"Our method is easy to use in daily life and can be adopted by anyone," says study director Bjorn Rasch, a biopsychologist.

But students need to understand the narrow connection between memory and sleep that is in play, warn researchers.

"You can only successfully activate words that you have learned before you go to sleep," says Schreiner. "Playing back words you don't know while you're asleep has no effect."

Yet an earlier study in June, as reported by Tech Times, does provide some evidence that sleep can play into improved memory, and that a lack of sleep can hinder memory.

Sleep, according to the study's researchers, strengthens the neural connections in the brain.

"But what's the underlying physical mechanism responsible for this phenomenon? Here we've shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory. We also show how different types of learning form synapses on different branches of the same neurons, suggesting that learning causes very specific structural changes in the brain," says senior investigator Wen-Biao Gan, professor of neuroscience and physiology and a member of the Skirball Institute of Biomolecular Medicine at New York University Langone Medical Center.

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