The main cause of cognitive impairment is Alzheimer’s disease. In the pathology of Alzheimer’s disease, the main factor is the accumulation of β-amyloid (Aβ) in the brain, forming plaques and causing inflammatory reactions, which ultimately damage brain neurons. In recent years, drugs have been developed that can reduce the level of accumulated Aβ. However, research evidence to date only supports the use of this drug in patients who have already developed symptoms of cognitive impairment; the drug fails to produce therapeutic effects before the symptoms appear. Alzheimer’s patients have an obvious accumulation of Aβ in their brains more than 10 years before the onset of symptoms. Therefore, to keep the brain young, we must take action long before symptoms appear to promote the effective clearance of Aβ in the brain.
In July 2021, the Journal of the American Medical Association (JAMA) Network Open published a large study involving more than 4,400 people aged 65 to 85 with intact cognitive abilities. The study has found that nighttime sleep, especially deep sleep, effectively reduces Aβ levels in the brain. Actually, many previous studies have already shown that lack of sleep can increase Aβ levels in the brain. In 2018, experimental results from the United States revealed the following: 20 healthy volunteers underwent brain scans to measure their Aβ levels after a sleepless night. The results found that just one night of sleeplessness could increase the Aβ in the region of the brain associated with memory by up to 5%.
Why is sleep, especially deep sleep, so important for clearing the Aβ from the brain? The brain has a lymphatic system similar to the rest of the body, and during sleep, the space between brain cells increases significantly, which helps cerebrospinal fluid flow through brain tissue and flush the Aβ from the brain. Therefore, sleep is a critical time for brain detoxification. Our brain produces various metabolic wastes every day, including Aβ, so a good night’s sleep, like taking a shower, is a daily necessity.
For many people, especially the elderly, deep sleep is priceless. One of the keys to getting deep sleep at night is to get exposure to natural light during the day, especially in the morning. Therefore, maintaining a regular sleep-wake time every day and taking a walk outdoors in the morning are good habits to keep your brain young.
Written by: Dr. William Chui
Originally posted on: HKEJ Health
Translated by: Cheuk Long Chan
