The scientific journal Sleep recently revealed a study which seemingly claims that sleep quality has a direct impact on health. In the study, the sleep issues of a large sample amongst which 2,800 people were 100 years of age and older was examined.

It appeared that 65 percent of the sample who slept for about 7.5 hours including naps had a good or very good quality of sleep. The study also claimed that once the variables such as demographic characteristics, socioeconomic status and health conditions were controlled 70 percent of older adults aged 100 and above had higher chances of good sleep quality than adults aged 65 to 79. It also seemingly appeared that 23 percent men were more likely to report good sleep when compared to women.

46 percent of the sample was apparently facing health problems and reported that they had worst sleep quality. This further seems to assert that the sleep quality has to be good to lead long and healthy life. People who had at least one chronic disease, felt anxious or were struggling with everyday tasks failed to report good sleep quality.

“Age and health conditions are the two most important factors associated with self-reported sleep quality and duration,” commented Danan Gu, PhD, principal investigator and lead author of the study and faculty of the Nohad A. Toulan School of Urban Studies and Planning at Portland State University in Oregon.

The authors believe that since China has a population of more than 1.3 billion people including the largest elderly population in the world it is a valuable resource for studying healthy longevity. Therefore, data of the 2005 wave of the Chinese Longitudinal Healthy Longevity Survey was included in the study. It comprised of 15,638 adults aged 65 and older, including 3,927 who were between 90 and 99 years of age, and 2,794 who were 100 years of age and older. All the participants were spread across China in its 22 provinces.

Data was collected by questioning the samples about their recent quality of sleep and the hours put in everyday in sleep including naps. Data was also collected from other socio-demographic and health status measures. In-home interviews were conducted to collect as this data.

The study revealed that if 84 percent of the participants were provided with good medical service then they enjoy good quality of sleep whereas if 56 percent were in good economic condition then they were being able to have a good sleep. Hence, good quality sleep is seemingly directly related to the access to healthcare and economic status.

“The majority of healthy elders could experience satisfactory sleep quality,” said Gu. “Sleep problems at oldest-old ages likely arise from a variety of physiological and psychosocial factors rather than aging per se.”

It is supposedly stressed by the studies that due to poor health conditions older adults aged 80 and over tend to have shorter or longer sleep duration than adults aged 65 to 79. However, when the health conditions were controlled the participants aged 100 and older were less likely to sleep for five or fewer hours per day than the youngest elders. These participants were more likely to sleep for 10 hours or more.

It is suspected by the authors of the study that there is a bidirectional relationship between sleep quality and healthy longevity. The study highlights that an exploration of causality had to be avoided due to the cross sectional nature of the study. However, the data of the 2005 will be compared to the 2008-2009 wave of the survey at the end of 2010.

The study was published in the May 1 issue of the journal Sleep.