The findings support the notion that changes in sleep duration over time may contribute to cognitive decline and early Alzheimer's.
Growing evidence suggests that sleep duration that is shorter or longer than the recommended seven hours per day may increase risk of cardiovascular disease and type 2 diabetes.
Elizabeth Devore, ScD, of Brigham and Women's Hospital, Boston, and colleagues examined data for more than 15,000 participants in the Nurses' Health Study.
Participants who slept 5 hours per day or less had lower average cognition than those who slept 7 hours per day.
Those who slept 9 hours per day or more also had lower average cognition than those who slept 7 hours per day.
Too little or too much sleep was cognitively equivalent to aging by 2 years.
Via Charles Tiayon