Many people suffer routinely from chronic sleep problems, attributing them to stress, children, pets or a snoring bed partner. A poor night’s sleep leaves you feeling miserable. You’re tired, irritable and not so sharp when working the next day.
However, there can be many more serious consequences from a rough night of sleep than just feeling “dull” or “off” the next day. Emerging research suggests that poor sleep and certain sleep conditions might be able to help us predict dementia.
Researchers at the Mayo Clinic in Florida recently explored a fascinating possible link between sleep disruptions and dementia. The retrospective study was presented in March at the annual meeting of the American Academy of Neurology this year; it found that those who act out dreams in their sleep might be at risk for dementia later in life. The study involved an MRI examination of the brains of 75 patients who had been diagnosed with a REM sleep disorder and were also believed to suffer from a form of dementia.
Autopsies confirmed that those with a REM sleep disorder, especially males, are five times more likely to develop a condition known as Lewy body dementia. Lewy bodies are protein deposits that hamper normal brain function.
While many haven’t heard of Lewy bodies dementia, it accounts for as much as 25 percent of all U.S. dementia cases—making it the second most common form of dementia in the elderly. In addition, Lewy bodies are commonly seen in patients with Alzheimer’s disease and Parkinson’s disease.
You may wonder how to spot this disorder in someone you care for—or even yourself. Here’s a short explanation: During REM sleep, your muscles (except for your diaphragm and your eye muscles) are completely relaxed. If your muscles weren’t relaxed, then you’d act out your dreams, which could be dangerous.
With REM sleep disorder, vocalizing and moving during your dreams is exactly what happens. Normally, activation of the neurotransmitter glycine prevents whole-body muscle movements (except for the eyes and the diaphragm). But in REM sleep disorder, activity of this neurotransmitter in the brainstem and pons is deficient, resulting in your mimicking the actions seen in your dreams. This could mean yelling, kicking, punching or leaping from the bed.
Though there is no cure for Lewy bodies dementia, this finding may help doctors diagnose the condition sooner and provide treatment for its symptoms.
Another more widely known condition is sleep apnea. While awareness of its symptoms is growing—the condition is marked by loud snoring, periods of held breath and explosive exhalation—most people are not aware of research that links apnea to dementia.
A 2011 study of elderly women in the United States showed that 45 percent of those with sleep apnea developed mild cognitive impairment or dementia, compared to 31 percent of those without that particular sleep disorder. Even after factoring in variables such as age, weight and smoking, the researchers found that sleep-disordered breathing was responsible for the mental decline of these study participants.
The Centers for Disease Control have estimated that about 24 percent of men and 9 percent of women have obstructive sleep apnea and about 80 to 90 percent of those with that condition go undiagnosed. Sleep apnea has been linked to sudden cardiac death and a number of other life-threatening conditions, including diabetes, hypertension and even cancer. Further study will be needed to understand whether treating sleep disorders such as these can change the risk for dementia.
According to the National Institutes of Health, sleep apnea is a condition that disproportionately affects men, African Americans, Latinos and Pacific Islanders, so it is especially important for individuals in those groups (and those who live with or care for them) to monitor their sleep habits.
More research is needed to determine whether acting out one’s dreams and sleep apnea can lead to dementia (meaning that they have a causative effect) or if they are merely associated with the condition (meaning that having a REM sleeping disorder does not necessarily mean you’re at risk for dementia.)
The existing research, however, underscores why all physicians, not just specialists, need to be trained to be aware of specific sleep disorders and why patients and those who care for and live with them should discuss serious changes in sleep patterns with their doctors.
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Just wanted to alert you to our two recent articles on sleep in the elderly and its relationship to cognition. Thought they might add an institutional research aspect to the wonderful story…
Are sleep onset/maintenance difficulties associated with medical or psychiatric comorbidities in nondemented community-dwelling older adults? Zimmerman ME, Bigal ME, Katz MJ, Derby CA, Lipton RB.
J Clin Sleep Med. 2013 Apr 15;9(4):363-9. doi: 10.5664/jcsm.2590.
Sleep onset/maintenance difficulties and cognitive function in nondemented older adults: the role of cognitive reserve. Zimmerman ME, Bigal ME, Katz MJ, Brickman AM, Lipton RB
J Int Neuropsychol Soc. 2012 May;18(3):461-70. doi: