Study Ties Poor Sleep Quality to Decline in Cognitive Development in Older Men

Researchers have discovered a strong association between poor sleep and cognitive decline in older men.

The study led by researchers at the California Pacific Medical Center Research Institute (CPMCRI), San Francisco, noticed that higher levels of fragmented sleep and reduced sleep efficiency was linked with a 40-50 percent increased risk of decline in cognitive abilities among older men.

The decline was similar to the effect of a five year age increase. Also, quality of sleep was associated directly with cognitive decline.

"It was the quality of sleep that predicted future cognitive decline in this study, not the quantity," lead author Terri Blackwell, MA, senior statistician at CPMCRI said in a news statement. "With the rate of cognitive impairment increasing and the high prevalence of sleep problems in the elderly, it is important to determine prospective associations with sleep and cognitive decline."

 A population based, longitudinal study conducted on 2,822 community-dwelling older men from six different clinical centers in the U.S was used in the study. The mean age of the subjects was 76 years.

Using a wrist actigraph, the researchers collected an average of five nights of objective sleep data from each subject.  They assessed the cognitive function of each person by evaluating the attention and executive function with the help of Trails B test. Executive function is the ability to plan and make decisions, correct errors and think creatively.  The researchers adjusted the results based on factors such as depressive symptoms, use of medication and comorbidities.

According to the President of the American Academy of Sleep Medicine, Dr. M. Safwan Badr, this new finding is a genuine revelation that healthy sleep does not mean just mean quantity of sleep but is rather good quality of sleep.

Most importantly sleep is crucial for the optimal cognitive functioning.

However, the underlying mechanism that links disturbed sleep and cognitive decline still remains a mystery. The researchers stated the need for further research in order to determine if the link between the two continue to exist after a longer follow up period.

The study was documented in the journal Sleep.