Make Sleep a Priority Chapter 8

Sleep and memory

What you learn during your waking hours is filed away for safekeeping as you sleep.


Your Sleeping Brain Builds a Library of Facts

The hippocampus is the initial storage site for fact-based memories. When you learn new vocabulary, math operations, people's names or historical facts, your hippocampus takes in the new information initially. During sleep, the hippocampus downloads these memories to the brain's cortex. This clears the decks in the hippocampus to make room for new information, and files away the facts you have learned so that you can recall them when you need to. READ MORE

In a 2010 University of California-Berkeley study, Matthew Walker, Ph.D, and his colleagues scanned the brains of sleeping subjects, observing the electrical activity in different parts of the brain. They found evidence that the hippocampus processes and stores material during non-REM sleep. At least half of our sleep time is spent in this stage. LESS


REM Sleep Reinforces Actions, Procedures and Skills

After your hippocampus has catalogued new information and stored it away during non-REM sleep, another memory consolidation process kicks in. During REM sleep, acts of coordination, physical skills, and other non-fact-based learning is filed away. READ MORE

In a Harvard University study, college students were taught a pattern of finger movements, similar to playing a song on a keyboard. Some of the students then slept for 12 hours, while the others did not. Then all subjects were asked to repeat the pattern they had learned. Those who had slept had a much easier time recalling and executing the sequence of movements. Also, functional MRI brain scans showed that the sleepers had much more activity in their cerebellum, an area of the brain that controls speed, coordination, and accuracy. LESS


How Sleep Apnea Affects Memory

Dramatic evidence of sleep's importance to memory has been found in people with obstructive sleep apnea (OSA). OSA sufferers are sleep-deprived because a structural defect temporarily blocks their breathing, causing them to wake frequently and gasp for air throughout the night. A 2008 study from UCLA's Department of Neurobiology scanned the brains of OSA sufferers and a control group of subjects who did not have the disorder. The researchers found that OSA sufferers have smaller mammillary bodies--globe-like structures on the underside of the brain which play a role in long-term memory. People with sleep apnea have been found to have mammillary bodies nearly 20% smaller than those of people without the disorder. READ MORE

OSA sufferers had long complained of memory problems and forgetfulness. This study was the first to connect physical deterioration of the mammillary bodies to the sleep disorder. LESS

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