While sleep is still a great mystery, researchers continue to chip away at aspects of it. A recent study has revealed a mechanism involved in something important to most of us: why we get more forgetful as we grow older. The study showed that the key appears to be the synchronization between slow (one every second or two) and fast (up to 12 per second) brainwaves during non-REM (rapid eye movement) sleep. When well synchronized, recent, short-term memories are consolidated, while when poorly synchronized (off by as little as 50 milliseconds), memories tend to be lost.
The study utilized 20 young adults and 32 people in their 60s and 70s; none showed any evidence of any form of dementia. They memorized 120 pairs of words, and then slept while monitored by electrodes on their heads. Then the next morning, the subjects were tested to determine how many of the word pairs they recalled. The results were that the young people had much better brain wave synchronization, and recall of the word pairs, than the older people.
The poor coordination of brain waves appears to be due to atrophy of the medial brain cortex, the area of the brain involved in producing deep sleep. Unfortunately, such atrophy occurs normally as one ages. There are plans to explore improving brainwave coordination in older people by applying magnetic or electrical stimuli to the scalp during sleep. But at present there appear to be no remedies available.
Here are three media articles on the study:
Older Adults’ Forgetfulness Tied To Faulty Brain Rhythms In Sleep
Older adults forget more because their brain rhythms don’t sync during sleep, study says
This keeps older adults from ‘saving’ memories during sleep
And here is the original study article:
Old Brains Come Uncoupled in Sleep: Slow Wave-Spindle Synchrony, Brain Atrophy, and Forgetting.
All four links have been added to Aging.