The results showed that people with ‘normal’ sleep duration of six to nine hours per night had higher self-reported scores for quality of life and lower scores for depression severity compared to short and long sleepers. Among patients who reported having perfect health, there were a higher percentage of normal sleepers, who also had significantly lower scores for depression severity compared to short and long sleepers with perfect health.
“These results are important because they provide more information about the importance of getting enough sleep, which is usually six to nine hours per night,” said principal investigator Charles Bae, neurologist at the Cleveland Clinic Sleep Disorders Center in Ohio.
“People may already expect that their quality of life could be decreased when they do not get enough sleep, but they may not realise that sleeping too much can also have a negative impact,” he said.
Bae and colleagues analysed data from 10,654 patient records, which were collected from January 2008 to May 2010.
“It was surprising to see that sleeping less than six hours and more than nine hours is associated with a similar decrease in quality of life and increase in depressive symptoms,” said Bae.
The findings were presented recently in Minneapolis at SLEEP 2011, the 25th Anniversary Meeting of the Associated Professional Sleep Societies LLC.
Classroom performance
Another study has found that sleep can help college students retain and integrate new information to solve problems on a classroom exam.
The study showed that performance by university undergraduates on a microeconomics test was preserved after a 12-hour period that included sleep, especially for cognitively-taxing integration problems.
In contrast, performance declined after 12 hours of wakefulness and after a longer delay of one week.
