Getting too little or too much sleep as we get older may affect how our brain functions, according to a study of almost 9,000 adults.
Researchers analyzed sleep and cognitive (brain function) data from 3,968 men and 4,821 women in the English Longitudinal Study of Aging. Respondents in the study reported on the quality and quantity of sleep over the period of a month.
In adults between the ages of 50 and 64, short sleep—less than six hours a night—and long sleep—more than eight hours a night—were associated with lower brain function scores. By contrast, in older adults (65 to 89 years) lower brain function scores were only observed in long sleepers.
Michelle A Miller of Warwick University says that “six to eight hours of sleep per night is particularly important for optimum brain function in younger adults.”
These results are consistent with our previous research, which showed that six to eight hours of sleep at night was optimal for physical health, including lowest risk of developing obesity, hypertension, diabetes, heart disease, and stroke.”
Interestingly, in the younger pre-retirement aged adults, sleep quality did not have any significant association with brain function scores, whereas in the older adults, those over 65 years, there was a significant relationship between sleep quality and the observed scores. The study appears in PLOS ONE.
“Sleep is important for good health and mental wellbeing” says Professor Francesco Cappuccio. “Optimizing sleep at an older age may help to delay the decline in brain function seen with age, or indeed may slow or prevent the rapid decline that leads to dementia.”
The Economic and Social Research Council funded the research.
*Image of “siesta” via Shutterstock