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Getting less than six hours sleep a night increases the risk of Alzheimer’s by almost a third

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It’s quite understandable if you’re having trouble sleeping. With the pandemic, who could relax during a time like this? But, not getting 7 to 8 hours a night only makes things worse.

Not getting enough sleep causes a number of physiological effects on the body, including risk of catching COVID-19.

But now, a new study has found a strong link between lack of sleep and Alzheimer’s diseases and according to it, individuals who are sleeping six hours or fewer are more likely to develop the devastating disease.

Scientists tracked and analyzed almost 8,000 Whitehall staff for more than 25 years.

Those sleeping six hours or fewer at 50 or 60 were more likely to develop the devastating disease.

In particular, dementia rates rose 30 percent among participants with consistently short sleeping patterns between the age of 50 and 70.

This was compared to peers who managed the seven or eight hours recommended by health experts.

This was irrespective of cardiovascular and metabolic conditions, such as diabetes, mental health issues like depression that are known triggers.

Corresponding author Dr. Severine Sabia, of the University of Paris, said sleep may clear rogue proteins from the brain called amyloid beta.

They clump together in the brain, killing neurons – leading to devastating memory loss and confusion.

Dr Sabia said:

“Regularly sleeping six hours or fewer per night during middle age is associated with a greater risk of dementia.”

Baroness Margaret Thatcher is famously said to have slept for only four hours a night. She had dementia when she died from a stroke in 2013 at the age of 87.

Dr Sabia added:

“The novelty of our study is using repeated measures starting in midlife to consider sleep duration at specific ages.

“We showed a consistent association between short sleep duration in midlife and risk of dementia.

“This study highlights the importance of having a good sleep for brain health. This adds to the increasing evidence that sleep is critical for health. These findings shall encourage good sleep hygiene.”

The international team, including British researchers, analyzed data on 7,959 civil servants who have been followed since 1985.

They were aged 35 to 55 when they were recruited to the Whitehall II ongoing health study.

The results published in Nature Communications adds to growing evidence linking lack of shut-eye to Alzheimer’s and other forms of dementia.

Dr Sabia said:

“These findings cannot establish cause and effect. But they suggest a link exists between sleep duration and dementia risk.”

It is known that during sleep, toxins are cleared out from the brain and other parts of the body – protecting against a host of illnesses including heart disease and cancer.

Dr Sabia continued:

“There are plausible biological hypotheses to explain the link between sleep duration and dementia.

“One of them concerns the role of sleep in the clearance of protein waste in the brain.

“During a waking period neuronal activity increases release of beta amyloid proteins, these proteins are then washed away from the brain during sleep.

“In the case of short sleep, clearance of these proteins might be altered and lead to accumulation of Amyloid beta in the brain.

“Accumulation of these proteins are observed in Alzheimer’s. Other mechanisms might also involve a role of sleep in neuroinflammation and atherosclerosis (hardening of the arteries).”

Globally, around 50 million people have dementia, and there are nearly 10 million new cases every year, according to the World Health Organization.

Dr Sabia said:

“A common symptom is altered sleep. However, there is growing evidence to suggest sleep patterns before dementia onset may contribute to the disease.

“Time spent sleeping is linked to dementia risk in the over 65s, but it is unclear whether this association is also true for younger age groups.”

Sleep duration was self-reported by the participants – some of whom wore wristwatch-like accelerometers overnight to confirm the accuracy of the results.

Dr Sabia said:

“The findings suggest sleep may be important for brain health in midlife.”

The Sleep Foundation in the US advises seven to eight hours specifically for over 65s.

With no cure in sight, there is an increasing focus on lifestyle changes that can help protect against it.

Dr. Sabia said:

“Sleep dysregulation is a feature of dementia but it remains unclear whether sleep duration prior to old age is associated with incidence.

“Here we report higher risk associated with a sleep duration of six hours or less at age 50 and 60, compared with a normal seven hours.

“Persistent short sleep duration at 50, 60, and 70 was also associated with a 30 percent increased risk independently of sociodemographic, behavioral, cardiometabolic, and mental health factors.

“These findings suggest that short sleep duration in midlife is associated with an increased risk of late-onset dementia.”

Changes in sleep patterns are common in dementia patients, believed to result from processes affecting the brain.

Observational studies have shown cognitive decline is fuelled by sleeping for too short, or too long. Dr. Sabia found no “strong evidence” for the latter.

Some studies have also linked changes in sleep patterns in older people with dementia.

Dr. Sabia said:

“Future research may be able to establish whether improving sleep habits may help prevent dementia.

“Public health messages to encourage good sleep hygiene may be particularly important for people at a higher risk of dementia.”

She added:

“Future research may be able to establish whether improving sleep habits may help prevent dementia.”

Earlier this year a study of almost 3,000 over 65s in the US found less than five hours of sleep a night doubled their risk of dementia.

Professor Derk-Jan Dijk, director of the Surrey Sleep Research Center, University of Surrey, and UK Dementia Research Institute group leader, said: “It is a solid piece of research adding to the growing evidence for a link between sleep and dementia.”

Dr Sara Imarisio, of Alzheimer’s Research UK, said:

“Many of us have experienced a bad night’s sleep and probably know that it can have an impact on our memory and thinking in the short term, but an intriguing question is whether long-term sleep patterns can affect our risk of dementia.

“This study cannot tease apart cause and effect and while it suggests that persistent lower sleep duration was linked with an increased risk of dementia, it did not find an association between longer than average sleep duration and dementia risk.

“While there is no sure-fire way to prevent dementia, there are things within our control that can reduce our risk.

“The best evidence suggests that not smoking, only drinking in moderation, staying mentally and physically active, eating a balanced diet, and keeping cholesterol and blood pressure levels in check can all help to keep our brains healthy as we age.”

Dr Elizabeth Coulthard, a dementia neurologist at the University of Bristol, said:

“This study adds new information to the emerging picture because sleep is reported in a middle-aged cohort who are then followed over 30 years.

“This means that at least some of the people who went on to develop dementia probably did not already have it at the start of the study when their sleep was first assessed.

“So, it strengthens the evidence that poor sleep in middle age could cause or worsen dementia in later life.”

Robert Howard, professor of old age psychiatry at University College London, said:

“We know that the first signs of Alzheimer’s disease appear in the brain 20 years before detectable cognitive impairment, so it is always possible that poor sleep might be a very early symptom of the condition, rather than a treatable risk factor.”

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