Researchers might disagree with Shakespeare's suggestion that sleep, "Nature's soft nurse," steeps the senses in forgetfulness. Instead they have come to believe slumber actively helps our brains consolidate what we learn and remember.
Experts distinguish between two broad categories of sleep based, in part, on brain wave patterns measurable using the electroencephalogram (EEG). Delta waves, the slowest rhythm of all brain waves, predominate during the deepest part of non-rapid eye movement (NREM) sleep. Meanwhile REM sleep, the kind of sleep most often associated with dreaming, is characterized by bursts of rapid eye movement. Over the course of a good night's sleep, NREM and REM sleep alternate cyclically.
While NREM and REM sleep are both critical for cognitive functioning, they may be important in the encoding and consolidation of different kinds of memories. NREM sleep may be particularly significant for declarative memory, our ability to recall the kind of fact-based information we might be tested on in school. Meanwhile REM sleep has been associated with procedural memory for how to do things like riding a bicycle or learning a new dance step.
Studies suggest depriving people of an adequate amount of sleep hampers their ability to learn new information. For example, researchers at the University of California San Diego found participants in their study were able to recall significantly fewer words from a list they just memorized when they had been deprived of sleep the previous night.
And, sleeping after something has been learned appears to help the brain consolidate new information in long-term memory. In one of their sleep studies, researcher Kenichi Kuriyama and his colleagues at Harvard Medical School had participants get a night's rest after doing a finger-tapping task on a computer keyboard for 12 minutes. They found that the participants' performance significantly improved the following day on parts of the task that had been most difficult for them.
The benefits of napping are also being investigated. In another study, the Harvard Medical School researchers found that people who napped for 60 to 90 minutes after learning the finger tapping task improved, while those who stayed awake didn't. However, the nappers' advantage disappeared overnight, once those who'd stayed awake were given a chance to catch some shut eye.
Experts agree that most people need seven or eight hours sleep to feel fully rested. Unfortunately, the ability to fall and stay asleep is often a casualty of aging. Reports of sleeplessness begin to increase in the 30s. And as the years pass, adults tend to spend more and more hours lying in bed waiting for the sandman. By age 60, getting a solid uninterrupted night of sleep can be a cause for celebration.
According to surveys, more than 30 percent of adults over the age of 60 say they have trouble sleeping and, not surprisingly, sleep-deprived older adults account for a disproportionate share of the prescriptions doctors write for sleeping medications.
The fact that aging is associated with changes in both memory and sleep
hasn't gone unnoticed. Researchers are investigating whether age-related declines and slowing in memory performance are associated with increased rates of insomnia and other sleep disorders among older age groups.
Here are some tips from the experts for getting a good night's sleep:
1. Fitness seems to help regulate sleep, so stay committed to your exercise program.
2. Do not drink alcohol, coffee, cola or tea after 7 or 8 in the evening.
3. Drink a glass of warm milk at bedtime.
4. Go to bed only when you are tired.
5. Make sure your bedroom is quiet and dark.
6. Learn some deep relaxation techniques.
7. Don't try to force sleep. Let it overpower you.
8. Read or partake in a relaxing hobby for a while if you can't sleep or if you wake up during the night.
9. Limit the number of hours you spend in bed, even if you've slept poorly.
10. If you had a sleepless night, try taking a short nap of no more than 45 minutes.
Posit Science works with more than 50 brain scientists at leading universities to develop programs that enhance cognitive abilities. The organization offers relevant information about brain science, tips for keeping your brain sharp, assessments for checking your brain fitness, and much more.
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