Those who take longer to fall into a deep sleep could be exhibiting an early sign of Alzheimer’s, research today suggested.
Studies have long warned that both the quality of amount of sleep can affect the risk of developing the memory-robbing condition.
But now scientists in China say people struggling to enter the rapid eye movement — or REM — stage of the sleep cycle may be showing a symptom of the disease.
This phase — the deepest of four we all go through every night — is vital for memory, learning and creativity.
They also found those who struggled to fall into a deep sleep quickly were more likely to have a build-up of two toxic proteins, amyloid and tau, in the brain — found in people with the condition.
Experts today said the findings suggested medication that can boost sleep, such as melatonin, could help delay disease progression — but warned further research was first necessary.
Dr Yue Leng, an associate professor in psychiatry and behavioral sciences at the University of California, San Francisco, said: ‘The delay in REM sleep disrupts the brain’s ability to consolidate memories by interfering with the process that contributes to learning and memory.
‘If it is insufficient or delayed, it may increase the stress hormone cortisol.
Studies have long warned that both the quality of amount of sleep can affect the risk of developing the memory-robbing condition
Alzheimer’s disease is the most common cause of dementia. The disease can cause anxiety, confusion and short-term memory loss
‘This can impair the brain’s hippocampus, a critical structure for memory consolidation.’
REM follows three phases of non-REM sleep, each deeper than the last.
The four phases take 90 minutes or more to complete, depending on age, and a person may cycle through them four or five times in a typical night.
Older people take longer to reach REM.
In the fresh study, scientists at the China-Japan Friendship Hospital in Beijing tracked the sleeping patterns of 128 volunteers, with an average age of 70.
Half had Alzheimer’s, and about one-third had mild cognitive impairment, a frequent precursor to Alzheimer’s. The rest had normal cognition.
Researchers tracked their brainwave activity, eye movement, heartrate and breathing during a night spent in the clinic.
They then divided the participants into early and delayed REM sleep.
Sleep deprivation can lead to obesity, memory loss, diabetes, heart disease, heightened and unstable emotions, impaired ability to learn and a reduced immune response, leaving you vulnerable to disease
In the fresh study, scientists at the China-Japan Friendship Hospital in Beijing tracked the sleeping patterns of 128 volunteers, with an average age of 70
The early group typically reached REM less than 98 minutes after falling asleep, while the late group took more than 193 minutes.
Those with Alzheimer’s were more likely to have delayed REM sleep, 16 per cent more amyloid and 29 per cent more tau than those with early REM sleep.
They also had 39 per cent less of a healthy protein called brain derived neurotrophic factor (BDNF), which drops in Alzheimer’s, according to the findings published in the Alzheimer’s and Dementia journal.
Previous research on mice has suggested melatonin can boost REM sleep and decreases tau and amyloid accumulation.
Other drugs that treat insomnia by blocking a chemical that suppresses REM sleep have also been shown to decrease tau and amyloid.
The scientists suggested that people who are concerned about their Alzheimer’s risk should ‘practice healthy sleep habits’ that help shift from light to REM sleep.
Dr Dantao Peng, an expert in neurology at the China-Japan Friendship Hospital and study senior author, added: ‘This includes treating conditions like sleep apnea and avoiding heavy drinking, since both can interfere with a healthy sleep cycle.
‘Patients taking certain antidepressants and sedatives that reduce REM sleep should discuss their concerns with their doctor, if they are worried about Alzheimer’s.’
Around 900,000 Brits are currently thought to have the memory-robbing disorder. But University College London scientists estimate this will rise to 1.7million within two decades as people live longer. It marks a 40 per cent uptick on the previous forecast in 2017
Recent analysis by the Alzheimer’s Society estimates the overall annual cost of the dementia to the UK is £42billion a year, with families bearing the brunt.
An ageing population means these costs — which include lost earnings of unpaid carers — are set to soar to £90billion in the next 15 years.
Around 944,000 in the UK are thought to be living with dementia, while the figure is thought to be around 7million in the US.
Alzheimer’s affects around six in 10 people with dementia.
Memory problems, thinking and reasoning difficulties and language problems are common early symptoms of the condition, which then worsen over time.
Dementia are expected to sky-rocket in the coming years, making a cheap screening tool vital to get to grips with the challenge.
Alzheimer’s Research UK analysis found 74,261 people died from dementia in 2022 compared with 69,178 a year earlier, making it the country’s biggest killer.
