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Dr. Datta's Research Links Sleep to Memory

dattaThe Anesthesiology neuroscience research program studies how consciousness works, particularly when patients are under anesthesia or sleeping naturally. Subimal Datta, PhD, Professor of Anesthesiology, has been researching the link between sleep and neurological disorders.

He is recognized as one of the world's leading sleep experts, with studies on insomnia, addiction, depression and anxiety disorders, including PTSD — all done through the lens of sleep.

Sleep is one of the best windows for studying the brain, and studies have shown that sleep carries with it a number of positive functions. Dr. Datta is focusing on how the brain regulates a certain sleep stage, called REM, or dreaming sleep. Particularly of interest is how the brain processes different types of memory during this stage.

"We encode information as we go through the day, and that information goes into short-term memory," Dr. Datta said. "If we don't sleep, the information is lost. It will simply disappear."

But if we sleep long enough to achieve the dream state, our brain is able to place that information in long-term storage.

"Sleep has four distinct stages of memory processing," said Dr. Datta. "Each stage does something different." In the first stage (N 2 sleep stage), the brain sorts the information into two piles, one to discard and one to keep. In the second stage (delta sleep), about 90 percent of the information is thrown away — typically information you already know. In the third stage (transition between non-REM and REM sleep), the brain strengthens the memories, and in the fourth (REM sleep), it puts memories into long-term storage.

Dr. Datta compares it to putting away your groceries. "After you shop, you have two choices. You can put the bags in the kitchen, and if you need something later, go through all the bags to find it.

"But if you have a system, where frozen foods go in the freezer, cold ones in the fridge and canned goods in the cabinets, you can easily find whatever you need. This is like the brain sorting memories for long-term storage."

In addition to the correlation between sleep and long-term memory, the research program is also looking deeper at the link between sleep and psychiatric disorders. Because the brain uses the same neurochemicals and processes in both experiences, if they can understand sleep, they may also isolate the source of stress, anxiety and other psychological issues.

"A lack of sleep can trigger early onset of all sorts of psychological disorders," said Dr. Datta. For example, if someone is genetically predisposed to Alzheimer's, Huntington's or Parkinson's, a consistent lack of sleep (fewer than six hours a night for 20 years), can trigger the disease 10 years earlier. Diabetes, hypertension and heart disease can also be triggered by deficient sleep.

Dr. Datta notes that, if you can't sleep a full six hours at a time, taking a nap during the day helps. "If you sleep four hours at night and two during the day," he said, "it's not equal but it's much better than just getting four."

Dr. Datta will continue his innovative research with the Neuroscience Research Program through a generous grant from the National Institutes of Health.

"A lot of progress has been made in understanding sleep and the brain over the last 50 years," he said. "While we may never know all there is to know about it, we continue to do what we can to understand it better."

Posted November 3, 2016

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