I feel a little hypocritical writing this article, because I only got six hours sleep last night. I know this puts me well short of the recommended amount of seven to nine hours prescribed by sleep scientists for optimal health. But does it really matter how much sleep we get? And who’s got the time to get that much sleep when there are emails to answer, Netflix to catch up on, and a triple-shot latte to get us through that 9am meeting?
It turns out, it does matter. A lot. Insufficient sleep has been linked to a host of health problems including obesity, cardiovascular disease and depression. Now, new research suggests that prolonged sleep deprivation may increase the risk of developing Alzheimer’s disease in later life.
Worldwide, 44 million people have Alzheimer’s, with the number projected to grow as the population ages. There is no cure, and current treatments are not very effective. This pernicious disease places a huge burden on health and social care systems, not to mention the emotional impact on patients and their loved ones.
Right now the research linking sleep patterns with Alzheimer’s is in its earliest stages. But it seems it’s not just the number of hours of sleep we get that matters, but how much time we are spending in the deep, non-rapid eye movement (NREM) phase. It is this sleep stage that enables new memories to be engraved on the brain, ensuring they are retained. When a person has Alzheimer’s disease, this NREM sleep phase is disturbed and it will continue to worsen as the symptoms progress.
Lack of NREM sleep allows neurotoxins to build up in the brain, with beta-amyloid protein being the one we need to worry about. Amyloid proteins are thought to be a waste product from the energy expended when brain cells communicate. These proteins are poisonous to brain cells, attacking their function and eventually killing them. Alzheimer’s disease is associated with the accumulation of this protein in the brain.
Sleep enables our brains to flush out these harmful toxins. One study of mice revealed how a type of drainage network exists within the brain, called the glymphatic system. This system kicks into high gear when we sleep, helping to wash away the harmful metabolic debris generated during brain activity during the day. However, when the mice were prevented from getting enough deep NREM sleep, there was an immediate increase in amyloid deposits in the brain.
This lack of sleep precipitates a vicious cycle whereby continued sleep deprivation results in a build-up of brain plaque, attacking the regions that generate deep sleep. More amyloid results in less NREM sleep, less NREM sleep results in more amyloid… and so on. Scientists believe this may constitute the first stage of Alzheimer’s, which can begin years before symptoms of the disease are presented. Famously (if anecdotally), former British Prime Minister Margaret Thatcher and US President Ronald Reagan survived on four to five hours a night – and both went on to develop Alzheimer’s disease.
So, if we should all be taking sleep more seriously, how can we help ourselves achieve the important NREM stage of slumber?
- Cut caffeine. Try to stay away from caffeine close to bedtime: half the caffeine you take in at 7pm is still in your body at 11pm.
- Limit alcohol. While a glass of wine may help you fall asleep initially, it will also alter your sleep pattern and the quality of your sleep.
- Establish a rhythm. Plan a relaxing routine 30-60 minutes before bed.
- Get a workout in. Daily exercise can help alleviate problems such as anxiety and depression which can interfere with sleep. It also raises your body temperature, with the ensuing decrease in core body temperature that follows helping us achieve better sleep.
- Turn off your device. Light slows down the production of melatonin, the hormone that helps us sleep, and the blue light from screens can keep us awake for longer and disturb the quality of our sleep.
A single night of poor sleep is enough to see damaging effects in the brain. No one is suggesting there is any direct link between the odd bout of bad sleep and serious illness, but getting enough of the right kind of sleep should be something we all prioritize – not only so we feel alert the next day, but to protect the health of our brains in the future.
For more about brain health and the influence of exercise and sleep, see this Fit Planet interview with neuroscientist Maurice Curtis.