Poor sleep and cognitive decline: the increased risk of too much or too little for middle age and older patients

The study not only allows for examining sleep patterns over a longer duration, but also considers other variables that may impact poor sleep and cognitive decline

Changes in sleep patterns are strongly associated with older patients who are already showing signs of dementia. Many seniors with dementia experience difficulty falling asleep, have fragmented sleep patterns, or are drowsy during the day. In some cases, these changes can show up in what is known as sundowner syndrome, in which a patient’s cognitive state slowly declines over the course of the day, getting worse as bedtime approaches. The link between poor sleep and cognitive decline impacts many older patients and may exacerbate symptoms for seniors with dementia.

Addressing poor sleep in middle age

Although the main focus of this body of research is on patients ages 65 and older who are already showing signs of dementia, some interesting new findings are showing that poor sleep habits in middle-aged patients may increase risk later on in life. Furthermore, even those age 65 and over, without any obvious signs of dementia, may be at greater risk of later onset, as a result of poor sleep.

Prolonged time in bed and risk of dementia onset for older patients

A recent article published in the Journal of the American Geriatrics Society reported the findings from a study examining the possible relationship between an early bedtime and sleeping more than eight hours a night, and the risk of developing dementia.¹

Sleep and cognitive data on almost 2,000 participants, ages 60 or older, was gathered at the start of the trial period. At the end of the trial, four years later, participants were screened for dementia. At the follow-up screening, 97 study participants were diagnosed with dementia. Researchers found that the risk of developing dementia was 69% higher for those subjects who slept more than eight hours, when compared to those who spent less time in bed.¹

Poor sleep and cognitive decline for middle age patients

As mentioned previously, most studies of dementia and sleep issues involve older patients. However, a study from 2021 used a cohort of almost 8,000 subjects as young as 50, yet found similar results.²

The results, published in Nature Communications, examined the connection between sleep duration and incidence of dementia. Study subjects were surveyed six times over the course of 25 years about their sleep habits, including how many hours they slept each night.

At the end of the study, 521 subjects were diagnosed with dementia, at an average age of 77. In analyzing the data, the researchers noted that study participants who routinely slept for six or less hours at ages 50, 60 and 70, were 30% more likely to be at risk of dementia than those who slept for seven hours.

The researchers also accounted for other potential factors that could affect sleep patterns or risk of dementia, such as physical activity, body mass index (BMI), or chronic health issues.² This study is particularly interesting because it not only allows for examining sleep patterns over a longer duration, but also considers other variables that may impact poor sleep and cognitive decline.

The take-away message for DCs is obvious — addressing poor sleep habits in both seniors without signs of cognitive decline and middle aged patients may reduce the risk for development of dementia later in life.

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