Sleep & Memory: Sleeping “Soundly”

A new study examined how sounds affect memory consolidation during sleep.

Participants were taught to associate 50 images with a random location on a computer screen. Each object was paired with a corresponding sound.

About 45 minutes later they took a nap of 90 minutes or less. This was long enough to enter deep, slow-wave sleep. But they didn’t nap long enough to enter rapid eye movement sleep – or REM sleep.

Twenty-five of the sounds were replayed as they slept. Participants were unaware of the sounds. Then they were tested again after waking from the nap.

Results suggest that the sounds improved their memory. Their performance was more accurate for the 25 objects that had been reinforced by sounds as they slept.

"The research strongly suggests that we don't shut down our minds during deep sleep," lead author John Rudoy said in a Northwestern University news release. "Rather this is an important time for consolidating memories."

Senior author Ken Paller told the New York Times that the method probably isn’t useful for teaching new information. But it may reinforce what you’ve already learned.

“One of our speculations is that SAT scores could be improved,” he said. He added that the technique might be able to help football players learn a playbook.

Recently the Sleep Education Blog reported that what you smell during sleep can affect your dreams. Learn more about sleep and memory.

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Deep Sleep: Alzheimer’s, CPAP & OSA

A new study examined the effect of CPAP therapy on sleep in people with obstructive sleep apnea and Alzheimer’s disease.

The study involved 52 adults with OSA and Alzheimer’s disease; they had an average age of 78 years. The effect of CPAP therapy was compared with fake, placebo CPAP. Sleep was measured by overnight sleep study.

Results show that even one night of CPAP therapy had a positive effect on sleep. People in the CPAP group had a lower percentage of stage 1 sleep than the placebo group; they also had a higher percentage of stage 2 sleep.

The AASM reports that stage 1 sleep tends to occur when you first fall asleep and after awakenings during the night. This sleep is very light; a slight sound can wake you up.

It is not as easy to wake you up during stage 2 sleep. During this sleep stage your muscles are more relaxed.

Three weeks of CPAP therapy also provided sleep benefits. Participants spent less time awake during the night after first falling asleep. They had a lower percentage of stage 1 sleep and fewer arousals.

They also had a higher percentage of stage 3 sleep. This is known as “slow-wave sleep” or “deep sleep.”

The authors report that disrupted sleep is common in people with Alzheimer’s disease and OSA. CPAP therapy can help them reach and maintain deeper stages of sleep.

In August the same research team reported that CPAP therapy produced long-term benefits for people with Alzheimer’s disease and sleep apnea. There also is evidence that chronic sleep loss could play a role in the development of Alzheimer’s disease.

The AASM reports that OSA can occur in any age group; but it is more common between middle age and older age. The severity of untreated OSA also tends to progress over time.

On SleepEducation.com you can answer these questions to learn more about your risk for sleep apnea. Get help for sleep apnea at an AASM-accredited sleep center near you.

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