It is possible to reduce the daily need for sleep with several hours. Research shows that the body then retains the same amount of non REM sleep, and instead cut down on REM sleep. The outcome is that the muscles get their rest, but the brain doesn’t get time to sort. The important post-learn-work will not happen. Things you thought were important are soon forgotten.
Sara Mednick of the University of California, San Diego, says that we would even benefit from taking an extra nap in the middle of the day: “Imagine a product that increases alertness, boosts creativity, reduces stress, improves perception, stamina, motor skills, and accuracy, enhances your sex life, helps you make better decisions, keeps you looking younger, aids in weight loss, reduces the risk of heart attack, elevates your mood, and strengthens memory. Now imagine that this product is nontoxic, has no dangerous side effects, and, best of all, is absolutely free. This miracle drug is, in fact, nothing more than the ‘nap': the right nap at the right time.”
Matthew Walker of the University of California, Berkeley describes how memories are transferred from the hippocampus to the cortex. In a research project, he trained two groups of people in memory exercises. One group took a nap at noon. And they improved their performance in the afternoon. The second group had worse results.