Better Sleep is a Protective Factor Against Dementia

Dementia is a Progressive Loss of Cognitive Abilities

Dementia is a progressive loss of cognitive abilities, such as memory, that is significant enough to have an impact on a person’s daily activities. It can be caused by a number of different diseases, including Alzheimer’s, which is the most common form. Dementia is caused by a loss of neurons over a long period of time. Since, by the time symptoms appear, many changes in the brain have already occurred, many scientists are focusing on studying the risk and protective factors for dementia.

Risk and Protective Factors for Dementia

A risk factor, or conversely, a protective factor, is a condition or behaviour that increases or reduces the risk of developing a disease, but does not guarantee either outcome. Some risk factors for Alzheimer’s disease and dementia, such as age or genetics, are not modifiable, but there are several other factors we can influence, specifically lifestyle habits and their impact on our overall health.

Lifestyle Habits and Their Impact on Our Overall Health

These risk factors include depression, lack of physical activity, social isolation, high blood pressure, obesity, diabetes, excessive alcohol consumption and smoking, as well as poor sleep. We have been focusing our research on the question of sleep for over 10 years, particularly in the context of the Framingham Heart Study.

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The Role of Sleep in Preventing Dementia

Sleep appears to play an essential role in a number of brain functions, such as memory. Good quality sleep could therefore play a vital role in preventing dementia. Sleep is important for maintaining good connections in the brain. Recently, research has revealed that sleep seems to have a function similar to that of a garbage truck for the brain: deep sleep could be crucial for eliminating metabolic waste from the brain, including clearing certain proteins, such as those known to accumulate in the brains of people with Alzheimer’s disease.

What is Deep Sleep?

During a night’s sleep, we go through several sleep stages that succeed one another and are repeated. NREM sleep (non-rapid eye movement sleep) is divided into light NREM sleep (NREM1 stage), NREM sleep (NREM2 stage) and deep NREM sleep, also called slow-wave sleep (NREM3 stage). The latter is associated with several restorative functions. Next, REM sleep (rapid eye movement sleep) is the stage generally associated with the most vivid dreams. An adult generally spends around 15 to 20 per cent of each night in deep sleep, if we add up all the periods of NREM3 sleep.

Loss of Deep Sleep Linked to Dementia

Participants in the Framingham Heart Study were assessed using a sleep recording — known as polysomnography — on two occasions, approximately five years apart, in 1995-1998 and again in 2001-2003. Many people showed a reduction in their deep slow-wave sleep over the years, as is to be expected with aging. Conversely, the amount of deep sleep in some people remained stable or even increased.

Strategies to Improve Deep Sleep

Knowing the impact of a lack of deep sleep on cognitive health, what strategies can be used to improve it? First and foremost, if you’re experiencing sleep problems, it’s worth talking to your doctor. Many sleep disorders are underdiagnosed and treatable, particularly through behavioural (i.e. non-medicinal) approaches. Adopting good sleep habits can help, such as going to bed and getting up at consistent times or avoiding bright or blue light in bed, like that of screens.

Conclusion

The role of deep sleep in preventing dementia remains to be explored and studied. Encouraging sleep with good lifestyle habits could have the potential to help us age in a healthier way.

Frequently Asked Questions

Q: What is dementia?

A: Dementia is a progressive loss of cognitive abilities, such as memory, that is significant enough to have an impact on a person’s daily activities.

Q: What is the role of sleep in preventing dementia?

A: Sleep appears to play an essential role in a number of brain functions, such as memory. Good quality sleep could therefore play a vital role in preventing dementia.

Q: How can I improve my deep sleep?

A: Adopting good sleep habits, such as going to bed and getting up at consistent times or avoiding bright or blue light in bed, like that of screens, can help improve deep sleep.