Sleep Page
The dream prescription
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.
Why sleep is good for health
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.
- It is thought, for instance, that regularly missing out on sleep affects how the body processes glucose, which, in turn, raises a person’s odds of diabetes
- Lack of sleep is also linked to obesity – and not just because we reach for fatty, sugar foods when we are tired
- Poor sleep appears to play havoc with hormones that control appetite, cutting levels of leptin, a chemical that makes us feel full, and boosting amounts of ghrelin, a hormone that fuels hunger pangs
- Sleeping well is also good for the heart. Long-standing sleep deprivation is associated with a higher heart rate, an increase in blood pressure and a rise in chemicals linked to inflammation, which may put extra strain on the heart
But what about the brain
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.
Sleep and cognition
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.
Why sleep may slow brain ageing
There are several theories on how sleep may help keep the brain healthy.
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Memory
Firstly, sleep is believed to be key to memory formation. Learning and memory are made up of three steps – acquiring new information, storing or consolidating it and recalling it.
The process begins with acquiring new information while we are awake and if we are sleep deprived, we find it hard to focus and so struggle to take it in.
Research suggests that the next step, the consolidation or long-term storage of that information, takes place while we are asleep.
Although the mechanisms are not fully understood, it is thought that different types of memory are stored during different stages of sleep. For instance, rapid eye movement (REM sleep) - when we have most of our dreams - and deep (or slow-wave) sleep seem to be involved in storing facts. Remembering how to do things may rely on REM sleep.
Sleep is also involved in the last stage of the process – retrieving memories. If the brain isn’t adequately rested, its overworked cells can’t coordinate properly and we can’t access information that we’ve filed away when we need it.
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Glymphatic System
Research is increasingly pointing to sleep having another important function in brain health. While we sleep, a waste disposal system is hard at work, clearing out toxins that have built up as the brain goes about its everyday work.
Known as the glymphatic system, it was only discovered in 2012. It is most active when we are asleep and is being increasingly implicated in a range of health conditions, including Alzheimer’s disease.
For instance, during sleep the system clears away beta-amyloid, a sticky protein that starts to gather in the brain ten to 15 years before Alzheimer’s is diagnosed and is a hallmark of the disease.
Research suggests that even one sleepless night increases the build-up of this protein.
Other even more recent work has shown that important immune cells called microglia are also most active when we are asleep.
These cells are key to fighting infections and repairing damage done by strokes, falls and other traumatic injuries.
Just as importantly, they play an important role in rewiring and reorganising the connections between brain cells as we learn new information and have new experiences. This ability of the brain to adapt to changes in our lives is called neuroplasticity and you can read about it in more detail in our Active Mind pillar.
How much sleep do I need?
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’.
How to sleep better
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:
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Daytime
- Get up at the same time every day
- Expose yourself to light during the day
- Exercise - as regular, physical exercise promotes good sleep
- Beginning after lunch, avoid caffeine
- Avoid driving when drowsy or sleep deprived
- If you are overweight, lose weight
- Don’t worry too much about the occasional night of bad sleep
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Evening
- Restrict food and fluids three hours prior to going to bed
- If you have trouble sleeping at night but doze off in the evening, such as watching TV, then listen to your body and go to bed earlier, or make yourself more alert by standing up and being active
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Nighttime
- Go to bed only when you feel drowsy enough to fall asleep
- Maintain a regular routine in preparation for bedtime to give your body signals it is time to settle down
- Keep the bedroom quiet and dark at night (if you have to get up at night, use a soft amber-coloured night light rather than turning on overhead lights)
- Maintain a bedroom temperature that is comfortable
- Avoid over-the-counter medications for sleep as they can have side-effects, particularly as we get older
- Dietary supplements for sleep, such as melatonin, may have benefits for some, but the scientific evidence is inconclusive
- Consider limiting any prescription sleeping pills (which can become less effective with regular use) to three nights a week, unless your doctor says otherwise
- Keep pets that disturb sleep out of the bedroom
- Keep smartphones, TVs and other electronics out of the bedroom
Is there any harm in taking a nap?
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.
What about a night cap?
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.
Research Details
March 2021
Page Last Reviewed
March 2022
Next Review Date
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