Improving Deep Sleep May Reduce Dementia Risk

Currently, over 55 million people have dementia worldwide. With nearly 10 million new cases occurring every year, it is more important than ever to address this neurological crisis. While there is currently no cure for the condition, mitigating one’s risk can help reduce the rising statistics.

According to a recent study, enhancing or maintaining deep sleep may help to do so. 

Deep Sleep and Dementia: What’s The Link?

Deep sleep refers to slow-wave sleep, which is the third stage of non-REM sleep. During this stage of sleep, there is slower brainwave activity, reduced muscle activity, and slower heart rate and breathing. This period of sleep is essential for waking up feeling rested and refreshed. It also maintains various cognitive functions and well-being, so any disruption to it can impact quality of life. 

In a new study from Monash University, researchers set out to determine the association between slow-wave sleep decline and dementia risk. 

“We know that the slow-wave sleep is critically important, and for an aging brain, it supports memory consolidation and helps to flush the brain of toxins that accumulate when we’re awake,” said lead study author Matthew Pase, PhD to Everyday Health. Dr. Pase is also an associate professor at the Monash School of Psychological Sciences and the Turner Institute for Brain and Mental Health in Melbourne, Australia. 

For the study, Dr. Pase and his team followed 346 participants with an average age of 69, who had been enrolled in the Framingham Heart Study. The participants completed two overnight sleep studies in time periods 1995 to 1998 and 2001 to 2003. There was an average of five years between the two studies, and all participants had no dementia at the time of the second overnight sleep assessment.

The participants were tracked for dementia diagnoses from the time of the second sleep study all the way to 2018, and the researchers noted that, on average, the amount of deep sleep had declined between the two studies. This then suggests that slow-wave sleep loss occurs as we age. As such, the researchers investigated the association between the development of dementia and slow-wave sleep loss. 

Loss of Deep Sleep Has Raises Dementia Risk

“We found that aging was associated with a decline in the amount of the deepest stages of sleep, known as slow wave sleep.

We then found that persons with greater declines in slow wave sleep over time had a higher risk of getting dementia over the next 17 years of follow-up,” Dr. Matthew P. Pase, CNN 

According to the findings of the study, published in JAMA Neurology, 52 cases of dementia were recorded over the next 17 years of follow-up, and each percentage decrease in deep sleep per year was associated with a 27 percent increase in the risk of dementia and a 32 percent greater risk of Alzheimer’s disease dementia.

This remained true after the researchers adjusted for age, sex, cohort, genetic factors, smoking status, sleep medication use, antidepressant use, and anxiolytic use. 

Since the study was observational, it failed to determine whether the decline in slow-wave sleep was directly responsible for an increased dementia risk. Yet, the researchers do believe that their findings suggest that slow-wave sleep loss may be a modifiable dementia risk factor.

Improving Deep Sleep

If you’re worried about the quality of deep sleep that you’re getting, the Sleep Foundation offers the following tips:

• Go to bed and wake up at the same time every day.
• Manage stress with relaxation exercises, deep breathing, yoga, and meditation
• Avoid or limit caffeine and alcohol
• Keep a comfortable bedroom by keeping your bedroom dark, quiet, and cool with a comfortable bed and pillows. Ear plugs, sound machines, and blackout curtains may also help. 
• Exercise regularly 
• If you are going to take sleep aids or medications, do so with caution, and only after consulting with a healthcare provider.

Want to know more?

If you’re interested in keeping your brain healthy and reducing your risk for dementia, here are the 7 healthy habits that can help reduce dementia risk.

References

Himali, J. J., Baril, A. A., Cavuoto, M. G., Yiallourou, S., Wiedner, C. D., Himali, D., DeCarli, C., Redline, S., Beiser, A. S., Seshadri, S., & Pase, M. P. (2023). Association Between Slow-Wave Sleep Loss and Incident Dementia. JAMA neurology, e233889. Advance online publication. https://doi.org/10.1001/jamaneurol.2023.3889