A study in the May 1 issue of the journal Sleep describes how changes in sleep that occur over a five-year period in late middle age affect cognitive function in later life. The findings suggest that women and men who begin sleeping more or less than 6 to 8 hours per night are subject to an accelerated cognitive decline that is equivalent to four to seven years of aging. A change to a shorter sleep duration was associated with lower scores at follow-up on three of the six cognitive tests, with reasoning, vocabulary and global cognitive status all being affected adversely.

“The main result to come out of our study was that adverse changes in sleep duration appear to be associated with poorer cognitive function in later-middle age,” said lead author Jane Ferrie, PhD, senior research fellow in the University College London Medical School Department of Epidemiology and Public Health in the U.K.

According to the authors, adequate, good quality sleep is fundamental to human functioning and well-being. Sleep deprivation and sleepiness have adverse effects on performance, response times, errors of commission, and attention or concentration. Furthermore, sleep duration has been found to be associated with a wide range of quality of life measures, such as social functioning, mental and physical health, and early death.