New research published in the journal SLEEP 
shows that middle-aged adults who have negative changes in sleep duration may experience a decline in cognitive function comparable to four to seven years of aging. The findings suggest that poor sleep can accelerate the aging process and lead to dementia at an earlier age.
The study involved more than 5,400 London-based public employees ages 45 to 69. The researchers used a series of questionnaires and tests to examine the participants’ sleep habits and cognitive function over a span of approximately five years.
Results show that the study participants who began sleeping less than six hours per night scored lower on tests for cognitive reasoning, vocabulary and overall cognitive function.
People who moved to sleeping an unusually long amount of hours – more than eight per night – had an even worse outcome. Long-sleepers had lower scores on all of the cognitive function tests except for short-term verbal memory.
The reason why long-sleepers had a worse cognitive outcome is unknown because the study relied on questionnaires to determine sleep length. It’s possible that the subjects who reported more than eight hours had poor quality of sleep due to frequent wakings.
Sleep apnea has been linked to a cognitive decline that is often mistaken for dementia. People with sleep apnea may wake hundreds of times per night without even knowing it. As a result, they may feel tired and “foggy-headed” the next day. Common treatments such as CPAP can reverse the brain tissue damage caused by sleep apnea and reverse cognitive impairment.
A small decline in memory is a normal part of the aging process and is common in much older adults. As the study shows, when found in middle-aged adults, memory problems and overall cognitive decline can be a red flag for sleep apnea or unhealthy sleep habits.
Invest in your long-term health by making six to eight hours per night a priority. If you are still fatigued most mornings you may want to consult a sleep specialist and get tested for sleep apnea or other sleep disorders.
