Study: Poor quality sleep leads to memory loss in seniors

Older people often have a harder time getting a good night’s sleep, and the lack of quality rest may be stealing more than their physical energy. A quality night’s sleep has a direct impact on the brain’s ability to recharge its memories, according to a new study published online this week by Nature Neuroscience journal.

As we sleep, the brain experiences several different cycles, including slow-wave sleep, which is crucial for recharging the brain and shifting our thoughts and experiences from short-term memory to long-term memory.

A University of California, Berkeley, research team combined sleep monitoring and memory testing to compare how sleep affected memory retention among two groups –younger people with an average age of 21 and older people with an average age of 75. All participants were shown pairs of words, then were tested on how well they could remember the pairings. Participants then underwent a sleep session while researchers monitored their brainwave patterns. Upon waking, participants were tested again on their ability to recall those same word pairings.

(A) EEG readings during deep sleep, young vs. older.  (B) Episodic memory change during deep sleep, young vs. older.

Source: “Prefrontal atrophy, disrupted NREM slow waves and impaired hippocampal-dependent memory in aging,” (fig. S2), Nature Neuroscience, January 2013.

The study revealed two key findings:

  • The older group experienced much smaller amounts of slow-wave deep sleep than the younger group did—barely 25 percent of what younger participants experienced.
  • The older group performed much worse on the memory testing after the sleep session than before it. The older group’s memory scores were 25 percent lower than the younger group’s scored prior to sleep, but the older group’s scores dropped to 50 percent of the younger group’s scores after the sleep session.

The findings also may inspire new ways for skilled nursing facilities and memory-care programs to combine efforts to improve both the quality of sleep and cognitive health for residents.

“We have discovered a dysfunctional pathway that helps explain the relationship between brain deterioration, sleep disruption and memory loss as we get older,” noted Matthew Walker, the study’s senior author. “And with that, a potentially new treatment avenue.”

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