When we think about aging, it’s hard not to worry about the possibility of cognitive decline. Science and researchers are working to better understand dementia—which currently has no cure—and to identify factors that could put certain people at risk. Now, a new study has called attention to a nightly practice that could keep your brain healthy. Read on to learn how you can decrease your dementia risk by making this evening adjustment.
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Ongoing research into dementia has helped identify a number of life changes that may actually stave off cognitive decline. Dusting off your French or Mandarin could be a proactive approach, as experts suggest speaking two or more languages could have a positive effect on long-term cognitive health and reduce your risk of Alzheimer’s disease—the most common form of dementia. In addition, a 2015 study published in The Journal of Neuroscience suggested that sleeping on your side can help your brain clear itself of waste most efficiently, lowering your risk of both Alzheimer’s and Parkinson’s disease. However, there is another sleeping habit that could be affecting your cognitive health—and it might have you considering changing your morning alarm.
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A study published April 28 in Nature Aging pinpointed the ideal amount of sleep for middle-aged and older adults—coming in at seven hours. When sleep hours were below or above that number, researchers from both the University of Cambridge in the U.K. and Fudan University in China found that study participants had poorer cognitive performance, affecting memory, processing speed, and the ability to solve problems. According to researchers, the association indicates that sleep duration could be a risk factor for cognitive decline as we age, which is a “hallmark symptom” of both Alzheimer’s disease and dementia.
Sadly, getting solid sleep becomes more difficult as we age, characterized by difficulty falling asleep, staying asleep, and decreased quality and quantity of sleep. According to researchers, finding solutions to these sleep challenges is vital for older populations.
“Getting a good night’s sleep is important at all stages of life, but particularly as we age,” study author Barbara Sahakian, ScD, FMedSci, professor in the Department of Psychiatry at Cambridge, said in a statement (via ScienceDaily). “Finding ways to improve sleep for older people could be crucial to helping them maintain good mental health and wellbeing and avoiding cognitive decline, particularly for patients with psychiatric disorders and dementias.”
When we don’t get the right amount of sleep, something called slow-wave sleep is disrupted, researchers said. According to Nature Portfolio, this is the third wave of sleep and is the deepest phase of non-rapid eye movement (NREM) sleep. Experts believe that memory consolidation occurs during this sleep phase, as well as amyloid deposition—the process when amyloid plaque clumps together and forms deposits in the brain, which some researchers think could be the main cause of Alzheimer’s disease.
Investigators noted that their findings are supported by earlier studies, which identified a link between nocturnal sleep duration and Alzheimer’s disease risk. In the present study, one of the most significant brain structures involved with sleep inefficiency was the hippocampus. As the hippocampus plays a role in both memory processes and in Alzheimer’s disease, researchers cited this finding as being especially important.
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Investigators studied data from 498,277 individuals logged in the U.K. Biobank. Participants between the age of 38 and 73 completed touchscreen questionnaires about their sleep practices and mental health and also completed different cognitive tests.
In addition to the link with cognitive performance, researchers found that getting seven hours of sleep was tied to better mental health. Getting any more or less than seven hours of sleep led to study participants experiencing more symptoms of anxiety, depression, and mania, as well as worse overall well-being.
Investigators said the link between sleep and cognitive issues is not yet definitive, but as previous studies have linked abnormal sleep to changes in brain structures in this population, the topic requires additional research.
“While we can’t say conclusively that too little or too much sleep causes cognitive problems, our analysis looking at individuals over a longer period of time appears to support this idea,” study author Jianfeng Feng, a professor at Fudan University, said in a statement. “But the reasons why older people have poorer sleep appear to be complex, influenced by a combination of our genetic makeup and the structure of our brains.”
The study was also limited, as it solely addressed hours of sleep and no other elements of sleep hygiene. The study pool included primarily white participants who self-reported their sleeping habits, meaning they were not objectively measured. Lastly, investigators did not consider overall health and how that could come into play with individual sleeping patterns.
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