Adverse changes in sleep duration associated with cognitive decline in middle-aged adults

May, 2011

A large long-running study has found that middle-aged adults whose night’s sleep had decreased from 6-8 hours or increased from 7-8 hours performed worse on some cognitive tests.

From the Whitehall II study, data involving 5431 older participants (45-69 at baseline) has revealed a significant effect of midlife sleep changes on later cognitive function. Sleep duration was assessed at one point between 1997 and 1999, and again between 2002 and 2004. A decrease in average night’s sleep from 6, 7, or 8 hours was significantly associated with poorer scores on tests of reasoning, vocabulary, and the MMSE. An increase from 7 or 8 hours (but not from 6 hours) was associated with lower scores on these, as well as on tests of phonemic and semantic fluency. Short-term verbal memory was not significantly affected. The magnitude of these effects was equivalent to a 4–7 year increase in age.

Around 8% of participants showed an increase from 7-8 hours of sleep over the five-year period (7.4% of women; 8.6% of men), while around a quarter of women and 18% of men decreased their sleep amount from 6-8 hours. About 58% of men and 50% of women reported no change in sleep duration during the study period. Some 27% of the participants were women.

The optimal amount of sleep (in terms of highest cognitive performance) was 7 hours for women, closely followed by 6 hours. For men, results were similar at 6, 7 and 8 hours.

Analysis took into account age, sex, education and occupational status. The Whitehall II study is a large, long-running study involving British civil servants. Sleep duration was assessed simply by responses to the question "How many hours of sleep do you have on an average week night?"

A very large Chinese study, involving 28,670 older adults (50-85), of whom some 72% were women, also supports an inverted U-shaped association between sleep duration and cognitive function, with 7-8 hours sleep associated with the highest scores on a delayed word recall test.

I would speculate that this finding of an effect of short-term verbal memory (in contrast to that of the Whitehall study) may reflect a group distinction in terms of education and occupation. The Whitehall study is the more homogenous (mostly white-collar), with participants probably averaging greater cognitive reserve than the community-based Chinese study. The findings suggest that memory is slower to be affected, rather than not affected.

Reference: 

Ferrie JE; Shipley MJ; Akbaraly TN; Marmot MG; Kivimäki M; Singh-Manoux A. Change in sleep duration and cognitive function: findings from the Whitehall II study. SLEEP 2011;34(5):565-573.

Xu L; Jiang CQ; Lam TH; Liu B; Jin YL; Zhu T; Zhang WS; Cheng KK; Thomas GN. Short or long sleep duration is associated with memory impairment in older Chinese: the Guangzhou Biobank Cohort Study. SLEEP 2011;34(5):575-580.

Related News

A small UK study involving 28 healthy older adults (20 women with average age 70; 8 men with average age 67), has found that those with higher levels of aerobic fitness experienced fewer language failures such as 'tip-of-the-tongue' states.

Findings from the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) Study, which followed 2,802 healthy older adults for 10 years, has found that those who participated in computer training designed to improve processing speed and visual attention had a 29% lower risk of dev

An Australian study involving 102 older adults (60-90) has concluded that physical fitness and arterial stiffness account for a great deal of age-related memory decline.

A long-running study involving 454 older adults who were given physical exams and cognitive tests every year for 20 years has found that those who moved more than average maintained more of their cognitive skills than people who were less active than average, even if they have brain lesions or b

Data from the English Longitudinal Study of Aging, in which nearly 4,000 older adults (60+) had their walking speed assessed on two occasions in 2002-2003 and in 2004-2005, those with a slower walking speed were more likely to develop dementia in the next 10 years.

Exercise activates brain networks in older adults

A study involving healthy older adults (55-85) found that recall was better after a session of moderately intense exercise, and several crucial brain regions showed greater activation.

Lowering blood pressure prevents worsening brain damage in elderly

A study involving 54 older adults (55-80), who possessed at least one risk factor for a stroke, found that those with

Perivascular spaces are fluid-filled spaces around the cerebral small vessels, commonly seen on brain scans in older adults. They have been thought to be harmless, but a new study challenges this belief.

Data from 3,105 older adults (65+) who had either heart surgery or cardiac catheterization has found that those who had heart surgery didn’t experience much greater cognitive decline compared with those who had the much less invasive, catheter-based procedure.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news