According to new research, people’s bedtimes and the amount of time they spend in bed (TIB) may increase their risk of acquiring dementia. Long TIB was related to greater cognitive deterioration in adults aged 60-74 years and men, even in those who did not develop dementia. The researchers recommend that older persons with long TIB or early bedtimes have their cognitive function monitored as a potential risk factor for dementia.
The study also discovered that even in people who did not develop dementia during the study period, extended sleep and early bedtimes were associated with cognitive deterioration. This discovery, however, was only seen in men and older persons aged 60 to 74.
Sleep and the risk of dementia
Sleep is a multifaceted biological process. Sleep time and quality changes associated with aging are linked to cognitive problems. The goal of this study was to “examine the associations of self-reported sleep characteristics (e.g., TIB, sleep timing, sleep duration, sleep quality, and EDS) with incident dementia, Alzheimer’s disease (AD), and cognitive decline, while accounting for potential interactions with demographic features and APOE genotype.”
The Mini-Mental State Exam (MMSE) was employed by the study’s authors to assess cognitive function. They diagnosed dementia using criteria from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The researchers then recorded the results of a statistical model that was adjusted for age, gender, and education. They utilized another model to account for BMI, smoking, alcohol consumption, diabetes, cardiovascular disease, and APOE genotype.
97 of the 1,982 individuals were diagnosed with dementia during the study’s average follow-up time of 3.7 years. At the outset, the competitors’ average age was 70.05. Women made up 59.6% of the sample, 83% were between the ages of 60 and 74, and 38.2% had no formal education.
Individuals who slept for more over 8 hours were 69% more likely to develop dementia than those who slept for 7-8 hours. The risk was also twice as high for those who went to bed before 9:00 p.m. as for those who went to bed at 10:00 p.m. or later. Baseline lengthy TIB, early bedtime and mid-sleep time, and early and late rise time measures were “significantly linked” with a higher reduction in cognitive deterioration as shown by MMSE scores among those who did not develop dementia during the trial.
Furthermore, while the dementia results were consistent across demographic groups, the cognitive decline alterations in those free of dementia were visible only in those aged 60-74 years, but not in those aged 75 and older.
Similarly, the study discovered that early and late rise times were associated with a higher MMSE score fall in men but not in women. Dr. Porter proposed many explanations for men’s increased risk of cognitive decline:
“Cultural expectations [concerning] traditional gender roles, and their impact on job choice and socioeconomic engagement, may potentially differentially affect men in rural China, given their frequent role as the primary ‘breadwinner,’ and their traditional engagement in more physically demanding and potentially stressful employment.”
MNT also addressed the topic with Dr. Michal Schnaider-Beeri, a psychiatry professor and head of the Sagol Neuroscience Research Center at Mount Sinai School of Medicine in New York. Dr. Beeri discovered a clear link between sleep and cognitive deterioration in men. “Some sleep disorders, such as sleep apnea, which is more common in men, could be part of the explanation,” she says.
The study, however, did not examine the existence or absence of sleep apnea, as Dr. Porter pointed out to MNT.