So much for elderly people taking good, long naps after lunch. Those who do are more likely to suffer from mental decline, according to French researchers. They studied results from 5,000 people over age 65 and found that the 20% who napped heavily fared worse on mental ability tests, the Telegraph reports. “These results suggest that excessive daytime sleepiness may be an early predictor of cognitive decline," said one researcher.
Another study found that nurses over 70 who slept too little or too much showed changes in brain chemistry that indicated early Alzheimer's. “There is already some evidence linking sleep duration and disturbances to cardiovascular health and diabetes, so it’s not surprising to see studies examining how sleep might affect cognitive ability over time," a researcher said. Seven hours of sleep a night is ideal, she added. (Read more nap stories.)