Blackwell T, Yaffe K, et al. Associations of objectively and subjectively measured sleep quality with subsequent cognitive decline in older community-dwelling men: the MrOS sleep study. Sleep 2014; 37: 655-663
Imagine if you could sleep your way to good health…
Far from being too good to be true, getting a good night’s sleep could be the dream prescription for a healthier body and brain.
In fact, scientists say it is time more of us woke up to the benefits of sleep.
A wealth of research shows that sleep – and how much or how little of it we get – affects our health in all sorts of ways.
The good news that it is never too late to change your habits to improve your sleep.
While most of us will be no strangers to feeling grumpy after a bad night’s sleep, sleeping poorly on a regular basis puts us at risk of host of serious medical conditions, including diabetes and heart disease.
Given the benefits of sleep for the body, it is perhaps no surprise that sleep is good for the brain.
It only takes a few sleepless nights for mental health to suffer, with anxiety, delusions and hallucinations all possible.
Plus, the brain ‘fogs’, making it more difficult to concentrate and make decisions, and the risk of accidents increases. In fact, some of the biggest disasters of our generation, from the explosion of the Challenger space shuttle to the Chernobyl nuclear disaster have been linked to lack of sleep.
When trouble sleeping continues, our risk of longer-term problems may rise. For instance, evidence is mounting that poor sleep raises the risk of cognitive decline and dementia – of which Alzheimer’s disease is the most common form.
While it’s far from a foregone conclusion that poor sleepers will go on to suffer memory problems, there has been some significant research which indicates that sleep may have an impact on our brain health
Some of the most striking evidence comes from a 2017 research paper that crunched together the results of 27 previous studies from around the world to try to determine just how big the effect of sleep on brain health might be.
This statistical technique, known as a meta-analysis, is considered the best way of weighing up the evidence on a topic, particularly when lots of different people have studied it in slightly different ways.
It revealed that people who slept poorly were at 55% higher risk of Alzheimer’s than those without sleep problems. Scans showed they also had much higher odds than others of having brain changes that can be a precursor to Alzheimer’s.
The researchers concluded that there are possible links between 15% of Alzheimer’s cases and poor sleep, adding: ‘As sleep problems are of growing concern in the population, these findings are of interest for the potential prevention of Alzheimer’s disease.’
Other compelling evidence on the importance of sleep for brain health comes from a 2013 study of almost 3,000 men aged 65-plus from around the U.S.
It found that those who slept poorly – defined as having trouble getting to sleep and/or waking up a lot during the night – were around 50% more likely to have suffered significant cognitive decline when tested again three or four years later.
Attention span, the ability to plan and make decisions, and abstract thinking had all deteriorated more. In some instances, the difference in decline between the good and poor sleepers was equivalent to five years of ageing.
But it is not just about quality of sleep – quantity may be important too. Other research has found that people who typically get just five hours of sleep or less a night and those who normally get nine hours or more do worse on a range of memory tests than those who average seven hours.
It is important to note that it hasn’t been definitively proven that poor sleep raises the odds of dementia – it is also possible that those in the early stages of the disease simply sleep more poorly. Regardless, there is a wealth of experimental evidence that leads experts to agree that sleeping properly is fundamental to good health.
There are several theories on how sleep may help keep the brain healthy.
In a landmark report in 2016, the Global Council on Brain Health (GCBH), an independent panel of scientists, doctors, academics and policy experts which provides trusted information on how to maintain and improve brain health, recommends getting seven to eight hours’ sleep each night for better brain and physical health.
It's important to note, however, that we all need a different amount and what is right for one person won’t necessarily suit another. So, while seven or eight hours will be right for many of us, some will naturally need much less and others will want more.
Experts say that rather than fretting over getting a certain number of hours of shut eye each night, we should try to cut back on late nights and simply do our best to sleep well.
The GCBH, which debates the latest brain health science to reach a consensus on what works and what doesn’t, also points out that sleep changes as we get older, becoming less deep and leaving us more vulnerable to disturbances. As a result, not only does it become harder to get to sleep but sleep becomes more fragmented, with older adults waking up more during the night.
Despite this, the report states that ‘people, of any age, can change their behaviour to improve their sleep’.
Many of the recommendations for a good night’s sleep revolve around sleep hygiene – rituals that can improve the ability to fall asleep and stay asleep. Others cover areas such as food and exercise.
The Global Council on Brain Health (GCBH) has these tips:
The truthful answer is that scientists aren’t sure. Research has shown, for instance, that an afternoon nap improves memory in middle-aged adults but, when those aged 50-plus nap, they do not feel better rested than non-nappers.
The GCBH says that naps of 30 minutes or less in the early afternoon are unlikely to disrupt night-time sleep. However, it advises against long, late naps.
While alcohol might make you drowsy, helping you fall asleep initially, it will likely disrupt your sleep later in the night. It can also make snoring and sleep apnoea, a disorder in which breathing repeatedly stops and starts during sleep, worse. The GCBH advises not drinking for two to three hours before bedtime. Smoking should be avoided for four to six hours before turning in.
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