Dementia is the name given to a group of symptoms linked to an ongoing decline in brain function, according to the NHS.
The condition affects about 850,000 people in the UK. About one in every six people over 80 years old have dementia.
Dementia symptoms include memory loss, mood changes, and finding it hard to carry out familiar daily tasks.
The most common types of dementia in the UK are Alzheimer’s disease and vascular dementia.
You could lower your risk of dementia risk by making sure you get more than five hours of sleep every night.
You’re more likely to develop dementia if you sleep for less than five hours a night, according to Japanese scientists.
But, sleeping for more than 10 hours could also increase your risk, they revealed.
The perfect amount of sleep you need every night is somewhere between there.
Between seven and eight hours of sleep has the lowest dementia risk, the scientists claimed.
You’re also less likely to die, from all causes, when you sleep for between seven and eight hours a night, they added.
“Given the beneficial effects of physical activity on risk of sleep disturbance, these findings indicate that not only maintenance of appropriate sleep duration, but also modification of lifestyle behaviours related to sleep may be an effective strategy for preventing dementia and premature death in elderly adults,” the researchers said.
“Age‐ and sex‐adjusted incidence rates of dementia and all‐cause mortality were significantly greater in subjects with daily sleep duration of less than 5.0 hours.”
The link between sleep and dementia risk is still unclear, according to the Alzheimer’s Society.
Different types of dementia are linked with different sleep problems.
“Researchers are also not yet sure which way the interaction goes,” said the charity.
“Whether poor sleep causes or exacerbates dementia, or if dementia leads to poor sleep.
“Some researchers believe that both of these theories could be true, and the relationship could be circular.”
It’s also unclear what causes the interaction, the Alzheimer’s Society added.
You could lower your risk of dementia by eating a healthy, balanced diet, according to the NHS.
A lack of regular physical activity also increases your dementia risk. Aim for about 150 minutes of moderate-intensity activity every week.