The surprising link between bedtime and dementia

  • Alzheimer’s disease, a common form of dementia, is one of them top ten Leading Causes of Death in the US.
  • New research suggests that time spent in bed and bedtime may affect dementia risk.
  • The 60 to 74 year olds were hardest hit.
  • Previous research has also highlighted the role of sleep quality in memory and dementia.

Sleep can affect physical and mental health and is linked to conditions ranging from heart disease and stroke to depression and obesity.

And a new one to learn published on September 21 in the Journal of the American Geriatrics Society has provided further insight into the role of sleep in dementia.

Researchers in China, Sweden and the UK looked at the sleep data of 1,982 Chinese people with an average age of 70 – none of whom had symptoms of dementia at the start of the study.

A median of 3.7 years later, 97 participants (5%) were diagnosed with dementia according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.

The main victims were between 60 and 74 years old. Men were also at greater risk, which contradicts the previous findings of many other dementia researchers.

“Most studies have found that women are twice as likely to have dementia than men. It’s unusual that this study found the opposite,” said Dr. Alex Dimitriu, Double Board Certified in Psychiatry & Sleep Medicine and Founder of Menlo Park Psychiatry & Sleep Medicine and BrainfoodMD.

The study found that longer bedtime (TIB) was associated with a significantly increased risk of dementia. Those who stayed in bed more than 8 hours were far more likely to show cognitive decline during a Mini Mental State Examination (MMSE) — a test that measures cognitive impairment.

So why do older people need to spend more time in bed?

“As we get older, we see a fragmentation of sleep states,” said Dr. Michael Breus, sleep specialist and clinical psychologist, to Healthline. This means “we don’t seem to get the same type of physically restorative sleep (stage 3/4) that we did when we were younger.”

Therefore, “it’s possible that people with poorer sleep quality may need more sleep time to compensate,” Dimitriu added.

Other factors may also play a role, explained Dr. Carl W. Bazil, PhD, Caitlin Tynan Doyle, Professor of Neurology at Columbia University College of Physicians and Surgeons.

Depression (which older adults are suitable for greater risk) can make it difficult to sleep, he explained. “But there are also many other conditions (like heart disease or diabetes) and the medications taken for them that can increase fatigue and the need for sleep.”

The time individuals went to bed was also highlighted as a crucial factor by the researchers. The early evening hours were considered the riskiest. The research states: “Every hour before bedtime [before 10 pm] was associated with a 25% increased risk of dementia.”

The authors of the study hypothesized that earlier bedtimes might be due to a disrupted circadian rhythm.

“Parts of the brain responsible for sleep management begin to change as we age. This affects our circadian rhythm cycles,” said Dr. David Rabin, PhD, neuroscientist, board-certified psychiatrist and co-founder of Apollo Neuro, a wearable stress relief device.

Age-related factors such as B. More frequent night-time toilet visits, “affect our good quality and our deep sleep,” Rabin continues. Accumulated sleep deprivation “results in a change in the brain structures that regulate the circadian cycle.”

Other influences could also play a role, Dimitriu said.

“It’s possible that people with early-stage dementia experience brain fatigue earlier during the day, which makes them want to sleep earlier,” he said. “‘Sundowning’ is a well-known effect in elderly dementia-prone people who can become confused and disoriented in the evenings.”

Consider study restrictions

One of the main disadvantages of research is that the TIB does not necessarily reflect time spent asleep. Scientists have found that sleep duration is a key factor in cognitive health and dementia risk.

Breus explained that a longer TIB could indicate an underlying sleep-related problem, like insomnia, that “could affect and aggravate this situation.”

A recent Canadian study also highlighted that those with insomnia were at a higher risk of memory loss.

Additionally, TIB does not take into account a person’s sleep quality – which is also thought to be important for cognition and dementia. For example, not getting enough deep sleep can severely impair memory (more on that later).

There is one final consideration to keep in mind.

“This study, like many others, are association studies and as such do not show cause and effect,” Bazil explained.

“So it’s never clear whether the observed association (in this case, short or long bedtimes or time to fall asleep) actually causes dementia or is indirectly related to it,” he added.

A key signal of dementia is memory loss. However, at all stages of life, “we know that good sleep is necessary for many, if not all, types of memory,” explained Bazil.

So what happens when you are in a state of slumber? With regard to memory, two main actions occur.

The first is the processing and “storage” of memories.

“Short-term memory is first stored in the hippocampus when it travels to the brain, which is the area where information is stored for short-term recall and use,” Rabin explained.

“When we sleep, information from the hippocampus is relayed to the higher cortical structures of the brain, allowing it to become long-term memory and integrate with previous memories,” he continued.

Rabin revealed that this process is called memory reconsolidation – and is particularly affected by poor REM sleep or shorter sleep durations.

Second, sleep is when our brains break down harmful toxins that can impair memory over time.

“When the brain is active during the day, it produces a lot of what we call ‘reactive oxygen species,’ or inflammatory waste products,” Rabin said. “When the brain is asleep and allowed to recover, particularly in deep and REM sleep states, [it] detoxifies and removes flammable waste products.”

A build-up of toxins eventually puts extra strain on the brain and prevents it from achieving memory reconsolidation.

“In summary, sleep quality can be just as important as sleep quantity,” Dimitriu said.

This study monitored the onset of dementia in older people – the period of life when symptoms are most likely to appear.

“Dementias such as Alzheimer’s disease often come with symptoms [among people] in their 60s, although early onset may occur in their 40s or 50s,” shared Dr. Sandra Petersen, Senior Vice President of Health and Wellness at Pegasus Senior Living, Healthline with.

She continued, “Dementia is a collective term for a group of diseases, the most common of which is Alzheimer’s, in which progressive changes take place in the brain.”

Petersen explained that common signs and symptoms of dementia are:

  • Persistent and ever-present difficulties with memory, cognition, and the ability to perform everyday tasks
  • loss of focus
  • inability to pay attention
  • loss of language skills
  • A decrease in visual perception
  • A loss of problem-solving skills
  • Impaired thinking and judgement

risk factors in dementia

While this new study uncovers sleep (among other things) as a risk factor in dementia, it’s not the only player involved.

“Researchers have considered a number of possible causes of dementia,” Petersen said. “We don’t know for sure, but it’s likely a combination of factors that contribute [its] development and progress.”

She revealed that scientists hypothesize that dementia can arise from:

  • Inflammation – resulting from poor sleep, poor diet, lack of exercise, and other unhealthy habits
  • The appearance of abnormal “tau” proteins in the brain
  • genetics
  • Untreated and persistent depression
  • The brain’s inability to use insulin properly

Sleep has long been associated with dementia. Poor sleep is believed to increase the risk, while people with dementia often struggle to get a healthy and restful night’s sleep.

This study did not examine some critical aspects of sleep, such as: B. the quality. However, it does highlight the link between dementia and TIB and bedtime – elements the paper called “poorly understood” and “rarely explored,” respectively.

More research is needed on how TIB and bedtimes may affect the onset of dementia.

But until then, the study authors said their findings “suggest that cognitive function should be monitored in older adults who report prolonged bedtime and advanced sleep timing.”


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