SLEEPY HEAD
How your dreams could be an early sign of Alzheimer’s – and the sleep aid that could slash your risk
Plus, other early signs of Alzheimer's to spot
People who take longer to enter the dream stage of the sleep cycle are more likely to develop dementia, suggests a new study.
It could be an early symptom of Alzheimer's disease, say scientists.
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The dream phase of sleep is known as rapid eye movement or REM.
It is one of four phases of sleep which take around 90 minutes to complete. A person may cycle through them four or five times in a typical night.
Recent studies have shown that both the quality and the amount of sleep we get may influence our risk of developing Alzheimer's.
Now, new research suggests that people who take "significantly longer" to start REM could be at risk of the disease.
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REM follows three phases of non-REM sleep which go from light to deep sleep.
Older people take longer to reach REM.
During REM sleep the brain processes memories, especially those that are emotionally charged, and puts them into long-term storage.
Study co-senior author Professor Yue Leng, of 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.
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"If it is insufficient or delayed, it may increase the stress hormone cortisol.
"This can impair the brain's hippocampus, a critical structure for memory consolidation."
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Researchers followed 128 people with an average age of 70 from the neurology unit of the China-Japan Friendship Hospital in Beijing. Half had Alzheimer's, and around a third had mild cognitive impairment, a frequent precursor to Alzheimer's.
The participants in the study slept overnight in the clinic so researchers could measure their brainwave activity, eye movement, heart rate and breathing.
Fitness trackers can capture some of this information, but it is less precise.
The researchers divided the participants into early and delayed REM sleep.
On average, the early group reached REM less than 98 minutes after falling asleep, while the late group reached it more than 193 minutes after falling asleep.
Those with Alzheimer's were more likely to have delayed REM sleep, according to the findings published in Alzheimer's and Dementia: The Journal of the Alzheimer's Association.
They also tended to have higher levels of the two toxic proteins, amyloid and tau, found in people with the condition.
Those with delayed REM sleep had 16 per cent more amyloid and 29 per cent more tau than those with early REM sleep.
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They also had 39 per cent less of a healthy protein called brain derived neurotrophic factor (BDNF), which drops in Alzheimer's.
Prof Leng said: "Future research should study the effects of certain medications that influence sleep patterns, as these may modify disease progression."
She added that melatonin can boost REM sleep, and studies in mice have shown that it decreases tau and amyloid accumulation.
Other drugs that treat insomnia by blocking a chemical that suppresses REM sleep also have been shown to decrease tau and amyloid.
People who are concerned about their risk for Alzheimer's should practice healthy sleep habits that facilitate the transition from light sleep to REM sleep, according to the research team.
Study co-senior author Dr Dantao Peng, of the Department of Neurology at the China-Japan Friendship Hospital in Beijing, added: "This includes treating conditions like sleep apnoea 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."
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The Sleep Foundation says on its website: "Since REM sleep occurs mostly during the second half of the sleep period, sleeping for too short a period may not allow time to complete all the REM sleep cycles.
"Thus, most recommendations for obtaining more REM sleep center around ensuring you are obtaining a sufficient quantity and quality of sleep."
First signs of Alzheimer's
ALZHEIMER'S is a brain disease that causes a slow decline in memory, thinking and reasoning skills.
Memory loss that disrupts daily life is one of the most common symptoms.
There are nine other symptoms to look out for - if you notice any of them, don't ignore them.
- Challenges in planning or solving problems
- Difficulty completing familiar tasks
- Confusion with time or place
- Trouble understanding visual images and spatial relationships
- New problems with words in speaking or writing
- Misplacing things and losing the ability to retrace steps
- Decreased or poor judgment
- Withdrawal from work or social activities
- Changes in mood and personality
Source: Alzheimer's Association
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