Going to bed early, sleeping more than 8 hours can increase the risk

Share on Pinterest
A new study finds a rather surprising link between sleep habits and the risk of dementia. Andre Rocha/EyeEm/Getty Images
  • New research suggests that the time you go to bed and the amount of time you spend in bed (TIB) may influence your chances of developing dementia.
  • Even in those who did not develop dementia, long TIB was associated with greater cognitive impairment in 60- to 74-year-olds and men.
  • The researchers suggest monitoring the cognitive function of older adults with long TIB or early bedtimes as a potential risk factor for dementia.

China has the world’s largest population of people with dementia, a neurodegenerative disorder. At least 6% of the elderlyor one in 20 people aged 60 or over, lives with dementia.

However, most studies of sleep and cognitive impairment have focused on Caucasian populations in North America and Europe.

A recent population-based study of elderly people in rural China linked prolonged sleep and early sleep time with an increased risk of dementia.

The study also found that even in those who did not develop dementia during the study time, there was still a degree of cognitive decline associated with prolonged sleep and early bedtimes. However, this particular finding was only evident in older people between the ages of 60 and 74 and men.

This clinical research appears in the Journal of the American Geriatrics Society.

Sleep is a complex biological process. Aging-related changes in sleep timing and quality are associated with cognitive impairment.

Today’s Medical News discussed this study with Dr. Verna Porter, neurologist and director of Dementia, Alzheimer’s Disease, and Neurocognitive Disorders at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the current research.

“It is important that studies assess non-white (Caucasian) populations, largely urban populations in North America or Western Europe. This study assesses rural adults in China […] with unique socioeconomic, cultural, educational and lifestyle practices,” said Dr. Porter.

Older adults in rural China tend to go to bed earlier, get up earlier, and have lower quality sleep than their white counterparts or people from urban areas.

research shows that dementia occurs more frequently in rural regions of the country than in its developed parts.

The aim of the present study was to “examine the associations of self-reported sleep characteristics (eg, TIB, sleep time, sleep duration, sleep quality, and EDS) with incident dementia, Alzheimer’s disease (AD) and cognitive decline, while taking into account their possible interactions with demographic characteristics and APOE genotype.”

The current cohort study recruited participants from the Shandong Yanggu Aging and Dementia Study, which involved rural elderly people in western Shandong Province.

Over several months in 2014, researchers conducted clinical examinations, in-person interviews and laboratory tests on 3,274 subjects aged 60 and older.

A total of 1,982 survivors from this reference group participated in a follow-up examination in 2018. The scientists studied sleep patterns at both baseline and follow-up.

They noted features including:

  • TIB
  • time to go to sleep
  • average sleep time (the average between the time you go to bed and the time you get up, to represent the circadian phase)
  • sleep latency (amount of time in minutes it takes to fall asleep at night)
  • sleep efficiency (proportion of time spent sleeping in bed)

The study authors used the Mini-Mental State Exam (MMSE) to measure cognitive function. They used Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria to diagnose dementia.

The researchers then entered the results of a statistical model adjusted for age, sex, and education.

They used another model to adjust for body mass index, smoking, alcohol consumption, diabetes, cardiovascular disease, and APOE genotype.

During the study’s average follow-up period of 3.7 years, 97 of the 1,982 participants were diagnosed with dementia.

The mean age of participants at baseline was 70.05. Women constituted 59.6% of the sample, 83% were between 60 and 74 years old and 38.2% of the subjects had no formal education.

The risk of dementia was 69% higher for people who slept more than 8 hours, compared to 7-8 hours. The risk was also double for those who went to bed before 9pm compared to 10pm or later.

Among those who did not develop dementia during the study, baseline long TIB, early bedtime and mean sleep time, and early and late rising time metrics were “significantly associated ” with greater reduction in cognitive decline as evidenced by MMSE scores.

Furthermore, although dementia outcomes were the same across demographic groups, changes in cognitive decline in those free of dementia were only evident among individuals aged 60 to 74 years, but not among subjects aged 75 or older. month.

Similarly, the study found that early and late rise times corresponded with a greater decline in MMSE score in men but not in women.

Dr. Porter offered possible reasons for the greater risk of cognitive decline in men:

“Cultural expectations [regarding] traditional gender roles, i [their] The impact on work choice and socio-economic commitment may affect men in rural China differently, given their frequent role as the primary “breadwinner” and their traditional commitment to more demanding work physically and potentially stressful.”

MNT also discussed this study with Dr. Michal Schnaider-Beeri, professor of psychiatry and director of the Sagol Neuroscience Research Center at the Sheba Medical Center at Mount Sinai School of Medicine in New York.

Dr. Beeri noted the strong association of sleep with cognitive impairment in men. “Some sleep disorders such as sleep apnea, [which is] predominant in men, could be part of the explanation,” he said.

However, as Dr. Porter pointed out MNT that the study did not address the presence or absence of sleep apnea.

Dr. Beeri was impressed with the broad scope of the study to cover sleep issues. Its unique population, large sample size and adjustment for factors such as age, sex, education and more made this a robust piece of work, he said.

The results, however, do not show causality. For example, the researchers were unable to pinpoint the exact reasons for age-related differences in cognitive decline. Sex differences in cognitive outcomes are still “poorly understood” as well.

The study also did not consider mood-related symptoms or daytime napping, which is common among older adults in rural China.

Another limitation of this study is the use of self-report, which carries the potential for recall bias. Multiple testing could have produced false-positive associations, the study authors noted.

Because the study participants came from a single region of China, the researchers cautioned when generalizing the results to other populations.

In addition, Dr. Porter mentioned that the follow-up period was short.

The study’s authors hope their findings “may partly bridge the knowledge gap” about people with low socioeconomic status.

They say their results should encourage follow-up of older adults “who report prolonged TIB and advanced sleep time, particularly in older adults. [ages] 60-74 years and men”.

Future work may explore how reducing TIB and adjusting sleep timing could slow the onset of cognitive decline and dementia.

Leave a Reply