Author: Melissa Burkley, PhD
Melissa Burkley received her Ph.D. in psychology from the University of North Carolina at Chapel Hill. Her scientific research has been featured in The New York Times, Cosmopolitan and Men's Health and she has made appearances on Oprah Radio and Martha Stewart Radio. Her freelance work has appeared in Poets & Writers Magazine and Hinnom Magazine. Her personal blog, entitled “The Writer's Laboratory,” teaches authors how to boost their creativity and improve their writing by incorporating psychological principles into their work. She also writes blog for Psychology Today called “The Social Thinker.”
Visit her website at www.melissaburkley.com
The older we get, the more a good night’s sleep feels like an unattainable dream.
Older adults tend to experience poorer sleep than their younger counterparts, both in terms of quantity and quality. As we age, our sleep becomes more fragmented. We spend more of our nights tossing and turning or getting up for frequent bathroom visits. Research shows that by the time we reach eighty, we only spend 70 to 80 percent of our night actually asleep, which leaves us awake an average of 1.5 hours per night.
To make matters worse, the quality of the sleep we do get in our later years isn’t as good as what we experienced in our youth. Our sleep becomes shallower and contains less of the deep, restorative sleep so important for mental health, including rapid eye movement (REM) sleep and non-REM sleep (sometimes called slow-wave sleep). For example, experts estimate that by the time you reach age seventy-five, you are only getting 10 percent of the non-REM sleep you experienced as a teenager. Importantly, these sleep impairments occur in older adults with and without sleep complaints, meaning that even if you don’t think your sleep has become impaired over the years, it probably has.
This information is not particularly shocking. Most of us are aware that older adults sleep less than teenagers. But most people assume this means we simply need less sleep as we age. That assumption is wrong. Older individuals need just as much sleep as anyone else, and without good quality sleep, their bodies and minds suffer.
Herein lies the problem. Since sleep issues are so common in our later years, older adults often fail to recognize how much their poor sleep is negatively impacting their mental and emotional health. In fact, a surprising 7 out of 8 older adults who experience poor sleep also suffer from another major mental health disorder like dementia or depression.
In the past, scientists would have looked at that statistic and assumed poor sleep was just a symptom of those other mental disorders, not a cause. But recently there has been a shift in such thinking. Sleep experts are beginning to examine the possibility that poor sleep may cause or mental health issues among seniors.
Dementia and Alzheimer’s Disease
Sleep plays a vital role in the memory process, no matter your age. When we are awake, the day’s events are stored in our short-term memory. When we sleep, our brain combs through our short-term memory and any information deemed important is transferred over to long-term memory. This transfer of memories from short- to long-term storage is a tricky process and can easily be contaminated by new information. For this reason, our brain does this delicate work when we are asleep and sheltered from incoming information.
Because of this process, our memories for new information significantly improves when we are given a chance to “sleep on it.” For example, one study gave a group of young adults and older adults a list of word pairs to memorize (e.g., car-mountain). Memory for these word pairs was tested immediately after and then again following a full night’s sleep. By the next morning, the younger adults remembered 50 percent more word pairs than the older adults—no surprise there. But what was interesting is that among the older adults, those who experienced the least amount of deep non-REM during the night showed the greatest memory impairments the next day.
This study, and many others like it, demonstrate that our brain needs good quality sleep in order to solidify new information and memories. When we are sleep-deprived, our brain acts like a sieve that allows important memories to slip through and be lost forever. This means that what may look like age-related dementia may instead be a case of age-related sleep deprivation. In fact, one study found that 80 percent of older adults suffering from sleep apnea—a sleep disorder where breathing repeatedly stops throughout the night—were wrongly diagnosed as having dementia.
To see just how much poor sleep contributes to poor memory, we need to look at research on Alzheimer’s disease. Alzheimer’s disease is a dementia disorder associated with the buildup of a toxic plaque in the brain called amyloids. Amyloids are like poison to our brain cells. When they accumulate, they kill off surrounding neurons, which in turn causes severe cognitive decline. But something that has confounded Alzheimer’s scientists for decades is that amyloid plaque does not accumulate in the area of the brain responsible for long-term memory storage (the hippocampus). Instead, it appears to accumulate most in the brain’s mid-region of the frontal lobe, which just happens to also be the area of the brain responsible for the generation of non-REM sleep. It’s no wonder than that 60 percent of Alzheimer’s patients suffer from at least one clinical sleep disorder (e.g., insomnia, sleep apnea).
To examine the relationship between sleep and Alzheimer’s disease more thoroughly, researchers at UC Berkeley conducted the same word-pair study described above but with two important changes. First, they did the study on a group of Alzheimer’s patients. Second, they used PET scans to assess the amount of amyloid buildup in the brain region responsible for non-REM sleep. The results were undeniable. Alzheimer’s patients with the greatest accumulation of plaque in the mid-frontal lobe had the greatest decline in non-REM sleep and also the greatest memory loss. Thus, poor sleep may be the missing link that explains the connection between amyloid buildup and memory loss.
If poor sleep plays a causal role in causing Alzheimer’s, then treating poor sleep represents an exciting new way to treat or even prevent the disease. A great deal of research still needs to be done on this topic, but there are already some promising results. First, evidence of sleep disturbances tends to appear several years before the onset of Alzheimer’s, suggesting that sleep issues may serve as an early-warning detector of the disease. Second, successfully treating sleep issues may slow or even reverse cognitive decline among Alzheimer’s patients. One study found exactly that when they treated a group of Alzheimer’s patients for their sleep apnea.
Memory loss isn’t the only issue we face as we get older. The CDC estimates that 5 percent of adults over age 65 experience depression. The CDC also estimates that 16 percent of suicide deaths are committed by adults over the age of 65 and senior men have the highest suicide rate of any group.
Many studies have found evidence that poor sleep either causes or exacerbates depression among the seniors. A review of 27 such studies found that depressed seniors are more likely than their non-depressed peers to experience sleep disruptions, including declines in overall sleep length, non-REM sleep length, and sleep depth.
Poor sleep also appears to reduce the effectiveness of depression treatment. A longitudinal study published in the journal Sleep examined the sleeping patterns of 1,800 older adults who were currently undergoing treatment for depression. The results showed that those suffering from chronic insomnia were nearly four times more likely to still suffer from depression after a year of treatment than those who did not have insomnia. Thus, insomnia appears to perpetuate older adults’ depression, even among those currently undergoing treatment.
Anxiety is more common among older adults than depression, affecting an estimated 8 percent of adults over the age of 65. And much like depression, there is a clear link between anxiety and sleep issues among older adults. A study published in Psychology and Aging found that among older adults, insomniacs displayed more anxiety symptoms than good sleepers. Another study found older adults who suffered from anxiety took longer to fall asleep and experienced more fragmented sleep than those who did not suffer from anxiety. Interestingly, this study found the participant’s subjective rating of their sleep quality was not associated with anxiety. This confirms that older adults are likely unaware of how poor their sleep is or how it is negatively impacting their mental health.
The implications from this body of work is clear. Older adults may scoff off their mental health issues as a normal or irreversible part of aging, or they may seek out a doctor’s help and get treatment with medication, but in both cases they are failing to address the true underlying cause. Matthew Walker, sleep expert and author of the bestselling book Why We Sleep, put it best when he said, “poor sleep is one of the most underappreciated factors contributing to cognitive and medical ill health in the elderly.” The good news is that poor sleep is treatable. By following strategies proven to improve your sleep, older adults can slow or even reverse these mental health issues.