Nearly everyone would agree that getting a good night’s sleep is important to how we feel and function. New research suggests getting the right amount of sleep — not too much or too little — is important for maintaining cognitive skills as we age.
The right amount of sleep is more challenging than ever given the demands of our 24/7 society. In the new study, researchers describe how changes in sleep over a five-year period during midlife can affect cognitive function later in life.
The findings, found in the journal Sleep, 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 equivalent to four to seven years of aging.
Among women, sleep duration of 7 hours of sleep per night was associated with the highest score for every cognitive measure, followed closely by 6 hours of nightly sleep.
Among men, cognitive function was similar for those who reported sleeping 6, 7 or 8 hours; only short and long sleep durations of less than 6 hours or more than 8 hours appeared to be associated with lower scores.
Individuals whose sleep increased from “7 or 8 hours” per weeknight scored lower on follow-up on five of six cognitive function tests, with the only exception being the test of short-term verbal memory.
Notably shorter sleep durations were also 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.
Surprisingly, an increase in sleep duration from six hours or less showed no evidence of a beneficial effect.
“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, Ph.D.
Although participants were mostly white-collar workers, the study group covered a wide socioeconomic range with a 10-fold difference in salary across the occupational hierarchy. Investigators adjusted for the effects of education and occupational position due to their known association with cognitive performance.
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.
“The detrimental effects of too much, too little and poor quality sleep on various aspects of health have begun to receive more attention,” Ferrie added.