The risk of dementia is greater in people who sleep six hours or less a night in middle age, a study has found.
Research found that people in their 50s and 60s who lacked normal sleep - defined as seven hours - were 30 per cent more likely to be diagnosed with dementia.
The study by University College London (UCL) examined how sleep patterns in midlife may affect the onset of dementia decades later, The Express reported.
Led by UCL and researchers from French research institute INSERM and published in Nature Communications in April 2021, researchers analysed data from nearly 8,000 people in the UK starting from the age of 50.
Dementia refers to a cluster of symptoms associated with brain decline.
The most common cause of dementia is Alzheimer's disease, a brain disorder that slowly destroys memory and thinking skills.
One study has delved into certain habits in middle age and how it could increase early onset of the condition.
Led by Dr Séverine Sabia, participants were assessed on a wide variety of measures, including being asked on six occasions between 1985 and 2016 how many hours they slept a night.
To assess the accuracy of this self-reporting, some of the participants wore accelerometers to objectively measure sleep time.
Over the course of the study, 521 participants were diagnosed with dementia, at an average age of 77.
The results of the study showed that people in their 50s and 60s getting six hours of sleep or less were at greater risk of developing dementia later in life.
Compared to those getting a 'normal sleep' of seven hours, people getting less rest each night were 30 percent more likely to be diagnosed with dementia.
Other studies have suggested that sleep patterns earlier in life may contribute to later dementia risk.
Both insufficient sleep and sleeping longer than average have been linked to a greater likelihood of developing dementia.
However, it has been hard to determine whether these sleep changes contribute to the disease or simply reflect early symptoms.
Lead author Dr Sabia said: "Sleep problems are known to occur in people with dementia, but it remains unclear whether sleep duration in midlife affects the risk of developing dementia at older ages.
"Here, by using a very long follow-up period, we have found that short duration sleep in midlife, assessed more than 25 years before mean age at dementia onset, is associated with dementia risk in late life."
She continued: "While we cannot confirm that not sleeping enough actually increases the risk of dementia, there are plenty of reasons why a good night’s sleep might be good for brain health. These findings confirm the importance of sleep hygiene for health."
"Many treatments that have been suggested to improve quality of sleep involve lifestyle changes," said the Alzheimer's Society.
The health charity added: "Regular sleep regimes, eating schedules and diets, exercise, and ensuring exposure to bright light in the morning are all ways that you can improve your sleep quality.
"However, more research is needed to indicate whether these activities have an effect on risk of dementia or disease progression."
Dementia symptoms
Early symptoms of dementia include:
- Memory problems, particularly remembering recent events
- Increasing confusion
- Reduced concentration
- Personality or behaviour changes
- Apathy and withdrawal or depression
- Loss of ability to do everyday tasks.
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