While many people associate a restless night of tossing and turning with headaches, fatigue and mood swings the next day, there’s an increasing amount of evidence that links poor sleep to dementia – an umbrella term that describes an array of symptoms caused by disorders of the brain that impact thinking, behaviour and even the ability to perform daily tasks.
Most people get between seven and eight hours of sleep each night and, while this varies from person to person, older people tend to enjoy a lighter slumber than when they were younger, with experts claiming this could have a negative effect on their memory.
This area is one of the key focuses of this year’s Sleep Awareness Week (which runs from August 5-11) with researchers examining how altered brain activity during sleep may be a risk factor for cognitive impairment, having found differences in the types of brainwaves that occur during sleep.
Dr Angela D’Rozario, NHMRC-ARC dementia research development fellow, tells Starts at 60. “These changes are thought to be part of the underlying mechanisms of linking poor sleep to dementia.”
Deep sleep is associated with big, slow brainwaves, which are important when it comes to the brain learning and retaining memories by transferring them from short-term to long-term storage. The weakening of these waves due to light or disrupted sleep is thought to contribute to cognitive decline and dementia.
In addition to impacting memory, poor sleep can also affect concentration and attention span, as well as influencing other cognitive functions. And, while the slow-waves of deep sleep are linked with learning and sleep-dependent memory consolidation, they’re also associated with the glymphatic system – the functional waste clearance pathway for the vertebrate central nervous system that clears toxins that build up in the brain when we’re asleep.
One of these toxins is beta amyloid, which is thought to contribute to Alzheimer’s disease when it builds up and clumps together in the brain.
“If you have reduced slow-wave sleep either through sleep disorders or sleep disruption, then it means that clearance isn’t as effective,” D’Rozario says. “Scientists in the area now are really trying to understand the mechanisms linking how poor sleep underlies the build-up of beta amyloid and pathology that leads to Alzheimer’s.”
Conditions such as sleep apnoea or insomnia can lead to disturbed and lighter sleep, but it’s also important to take note of how you’re feeling and what’s normal for you. If you regularly sleep six hours a night and you feel fine, it’s unlikely to be an issue, but if you’re suddenly sleeping less and feeling unrefreshed or unable to function properly the next day, it could be a sign of an underlying or undiagnosed issue.
In other cases, it could be something as simple as napping too much during the day, poor diet or a lack of exercise that is keeping you up at night, with D’Rozario explaining: “There is now more evidence to show that sleep is a risk factor for dementia. It’s a modifiable risk factor.
“Lots of the things we can’t change like our genetic make-up and so on, but some things we can change.”
Always talk with a health professional about your sleeping habits and about the best treatments for individual circumstances.
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