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Sleep plays a vital role in memory retention


Your memory is getting worse. If you don't write it down you can forget to do everyday tasks like picking up groceries or the kids after school. You chalk it up to stress or getting older, but your sleeping habits could be affecting your memory as well. 

Dr. Phyllis Zee is a professor in neurology and chief of the division of sleep medicine at Northwestern University’s Feinberg School of Medicine in Chicago. She joins us today to discuss the impact sleep has on your memory.


How long you sleep isn’t the only thing to worry about when it comes to sleep and memory retention. The type of sleep you get also plays a role as well. You go through two types of sleep cycles at night: REM sleep, which occurs in the last two or three hours of your sleep, and non-REM sleep, which is a deeper sleep that occurs in the first half of the night.

Non-REM deep sleep is responsible for processing your memories. During this non-REM sleep your brain stores two different types of memories, declarative and sensory. Declarative memory is stored during that first sleep cycle during the night. 

"So it’s thought that the slow wave sleep, that non-REM sleep, is more important for consolidating what we call that declarative memory," says Zee.

Age affecting your sleep

As you get older, you tend to not get as much sleep as you used to. This cuts down on the amount of the non-REM deep sleep that you get. Those with memory impairment get even less deep sleep than those without.

"That amount of deep sleep starts to go down naturally even in healthy older adults," says Zee. "And of course those with memory impairment -- such as you know cognitive impairment and Alzheimer’s disease -- that amount of deep sleep tends to even decrease even further." says Zee.

While a solution to this would be to take naps throughout the day to get those full eight hours, even if you have problems sleeping through the night, frequent disruptions in your sleep cycle are just as detrimental as not getting enough sleep in the first place.

"Just disturbing the sleep, this fragmentation of sleep, doesn’t mean you have to be awake completely but these very short bursts of arousals, especially if you’re already getting into deep sleep, can be just as detrimental to your memory formation as that of getting not enough sleep.” says Zee.