Why experts believe deep sleep could stave off dementia 

Several new drugs to treat dementia have made the headlines recently, but with concerns about the cost — let alone when they might become available on the NHS — and worrying potential side-effects (such as brain swelling), the news won’t change the lives of those affected today.

However, there may be a far more low‑tech approach that could make a more immediate difference to those with early signs of the disease.

Something as simple as getting a good night’s sleep may help older people stave off memory loss caused by Alzheimer’s disease — which is the most common type of dementia.

That’s according to new U.S. research published in the journal BMC Medicine, which shows that people with signs of the disease — detected by brain scans rather than symptoms — may be protected from memory loss if they have good-quality, deep sleep.

This news comes as UK researchers have recently embarked on a project looking at how boosting sleep quality could help improve the symptoms of people diagnosed with the disease.

Experts believe that, over the years, deposits of amyloid — called plaques — build up around brain cells and deposits of tau form tangles within the cells, causing an inflammatory response that damages the brain (file image)

All this could have important implications for the treatment of Alzheimer’s, because sleep quality is something you can change — unlike other factors that contribute to dementia, including age (the likelihood of developing Alzheimer’s disease doubles every five years after you reach 65).

As one of the researchers behind the new U.S. study explains: ‘With a certain level of brain pathology [i.e. changes that indicate disease], you’re not destined for cognitive symptoms or memory issues’.

Dr Zsófia Zavecz, a postdoctoral researcher at UC Berkeley’s Center for Human Sleep Science, told Good Health: ‘People should be aware that, despite having a certain level of pathology, there are certain lifestyle factors that will help moderate and decrease the effects. One of those factors is sleep and, specifically, deep sleep.’

This is the restorative stage of sleep, when the body repairs itself and stores memories from the day. Alzheimer’s disease is linked to an abnormal build-up of two proteins called amyloid and tau.

Experts believe that, over the years, deposits of amyloid — called plaques — build up around brain cells and deposits of tau form tangles within the cells, causing an inflammatory response that damages the brain.

The first areas to be affected are those associated with memory storage, including the hippocampus and entorhinal cortex in the temporal lobe.

In the new study, the researchers recruited 62 healthy adults over the age of 65. None of them had been diagnosed with dementia before the trial.

Researchers used a positron emission tomography (PET) scan to measure the amount of amyloid deposits in their brains; their sleep was then monitored with an electroencephalography (EEG) machine (which measures brain wave activity via small sensors attached to the scalp).

Brain waves change according to the different stages of sleep — deep sleep is characterised by slow waves, and lasts up to 40 minutes per sleep cycle (typically, a person has four to six sleep cycles per night).

This is when the brain downloads recent memories and stores them in a more permanent bank in the neocortex, which is part of the sheet of neural tissue that forms the outside wrinkled surface of the brain.

The PET scans revealed that half of the participants had high amounts of amyloid deposits (the other half had no obvious disease) and, among this group, those who experienced more deep sleep performed better on memory tests. Only the deep sleep stage of the sleep cycle was found to help preserve memory.

‘One explanation is that during deep sleep specifically, memories are replayed in the brain — and this results in a neural reorganisation that helps stabilise the memory and make it more permanent — a process we call memory consolidation,’ says Dr Zavecz.

What’s in a name? 

This week: Rugby jersey finger

Also known as jersey finger, this describes a tear in one of the flexor tendons, which runs from the tip to the knuckle of each finger, and allows it to grip and bend.

‘The tear typically happens in rugby when a player grabs an opponent’s shirt [or jersey], only for that person to then pull away, forcing the fingers to extend while remaining in a tight grip,’ explains Gavin Schaller, a consultant hand and wrist surgeon at West Hertfordshire Teaching Hospital NHS Trust. 

‘When the tendon is ruptured in this way, the joint at the tip of the finger will become painful and you’ll lose the ability to bend it.’ 

You need to rest your finger and apply ice to reduce inflammation. If you can’t move your finger, seek medical attention — surgery will be required if it’s completely torn.

‘It’s important the repair is done quickly, ideally within two weeks,’ says Mr Schaller. 

‘If left untreated, it may retract a long way from where it was originally attached and so will require more complex repair surgery.’

Another theory is that deep sleep helps support ‘the brain’s capacity to form new neural connections’ and provides ‘an optimal brain state for the clearance of toxins interfering with healthy brain functioning’.

Short naps during the day may have the same beneficial effect, she says, but adds: ‘This remains to be tested in further studies.’

One puzzle is why some people who have lots of signs of severe disease in the brain have almost no symptoms, yet others with very few plaques and tangles have severe symptoms.

‘If we believe that sleep is so critical for memory, could sleep be one of those missing pieces in the explanatory puzzle that would tell us exactly why two people with the same amounts of vicious, severe amyloid pathology have different memory?’ suggests Matthew Walker, a professor of neuroscience and psychology at the University of California, Berkeley, and a senior author of the study.

‘If the findings supported the hypothesis, it would be thrilling, because sleep is something we can change.’

However, the study did have its limitations, admits Dr Zavecz: ‘Our study has shown that sleep modifies the effect of amyloid protein on memory function, but it did not prove causation.’

In other words, it could be something else that happens when we sleep deeply that protects our memory.

So how can older adults ensure they get better quality deep sleep?

Dr Zavecz advises: ‘Stick to a regular sleep schedule, stay mentally and physically active during the day, create a cool and dark sleep environment, and minimise things like coffee late in the day and screen time before bed.

‘A warm shower before turning in for the night has also been shown to increase the quality of deep, slow-wave sleep.’ But sleeping pills are unlikely to help.

‘In general, classic sleeping pills have not proved especially useful in that regard,’ says Professor Walker. ‘However, a well-proven method is cognitive behavioural therapy for insomnia, or CBTi.’

This therapy helps people control negative thoughts and worries that interfere with their sleep, and also teaches them better sleeping habits.

‘In addition, we and others have been pioneering brain stimulation technology for boosting deep sleep,’ he says.

This technique, called direct current brain stimulation, involves sending a mild electric current (you don’t feel it) into the brain. It has already been shown to amplify the size of deep sleep brainwaves — and can also almost double the amount of memory benefits you get from sleep, Professor Walker says his research shows.

The question now is whether the same technology can be used to help older adults and those with dementia. ‘The technique is still years away from clinical trials, but we’re getting there,’ Professor Walker told Good Health.

Separately, researchers at the University of Surrey in the UK are looking at the role of good-quality sleep in protecting memory in people already living with dementia. The university was awarded £1.7 million for further research into the sleep and circadian rhythms of people diagnosed with the condition.

As Professor Derk-Jan Dijk, director of Surrey Sleep Research Centre at the university, explained: ‘People living with dementia tend to have issues with sleep and, often, their memory is seemingly worse after a bad night.

‘Good-quality sleep is integral to our cognitive health, and now we need to test whether improving the sleep of those living with dementia will slow down the progression of the condition and preserve an individual’s memory for longer.’

Researchers will use digital monitoring devices that can sense movements and physiological signals as the patients sleep.

Professor Dijk added: ‘A major advantage of the novel digital technologies we’re working with, many of which are contactless, is that they pose very little burden on the participant and can be used to monitor sleep and circadian [body clock] rhythms in the home environment for weeks, months and years.’

The Surrey team will also continue to test new ways to improve sleep, including changing brain waves using auditory stimulation, and improving lighting to help reset the body clock for better sleep.

Dr Richard Oakley, associate director of research at the Alzheimer’s Society, said: ‘We know from our own research that 40 per cent of cases of dementia could be prevented by people taking regular exercise, eating a healthy, balanced diet, not smoking and keeping blood pressure in check.

‘This [new U.S.] study showed how sleep is important in maintaining a person’s memory when there are signs of Alzheimer’s disease in the brain.

‘While people in the study with higher levels of the rogue protein amyloid — linked to Alzheimer’s — had better memory after a night of deep sleep, we can’t say for sure that one caused the other. This will need exploring in further studies,’ he adds.

To find out more about Alzheimer’s, visit alzheimers.org.uk, where there is also an interactive symptom checklist.