Scientists have recently revealed that both the quality and duration of our sleep might play a role in our risk of developing Alzheimer’s disease.
Scientists have recently revealed that both the quality and duration of our sleep might play a role in our risk of developing Alzheimer’s disease.
A current study indicates that individuals who take much longer to enter the dream phase of sleep, referred to as rapid eye movement (REM) sleep, might be experiencing an early indicator of the disease.
REM sleep follows three stages of non-REM sleep, each progressively deeper. Completing all four stages generally takes about 90 minutes or more, depending on a person’s age, and typically, a person cycles through these stages four to five times in one night. Older adults usually take longer to reach the REM stage.
During REM sleep, the brain works on processing memories, particularly those tied to emotions, and helps store them for the long term.
“The postponement in reaching REM sleep disrupts how the brain consolidates memories by interfering with the systems crucial for learning and memory,” explained Yue Leng, PhD, an associate professor at UCSF’s Department of Psychiatry and Behavioral Sciences.
“When REM sleep is inadequate or delayed, it may elevate cortisol, a stress hormone,” Leng noted, who is affiliated with the UCSF Weill Institute for Neurosciences. “This can negatively affect the hippocampus, which is vital for memory consolidation.”
Leng is a co-author of the paper published on January 27 in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association.
Increased levels of amyloid and tau proteins
Researchers monitored 128 individuals with an average age of 70 at the neurology unit of the China-Japan Friendship Hospital in Beijing. Half of them had Alzheimer’s, while about one-third exhibited mild cognitive impairment, often a precursor to Alzheimer’s; the remaining participants exhibited normal cognitive function.
The study participants stayed overnight in the clinic, allowing researchers to monitor their brainwave patterns, eye movements, heart rate, and breathing. Although fitness trackers can gather some of this information, they are less accurate.
The researchers categorized the subjects into those with early REM sleep and those with delayed REM sleep. On average, the early group entered REM sleep less than 98 minutes after falling asleep, whereas the delayed group did so after more than 193 minutes.
Those diagnosed with Alzheimer’s were more inclined to experience delayed REM sleep and generally had elevated levels of the two harmful proteins, amyloid and tau, commonly found in individuals afflicted with the disease.
Subjects with delayed REM sleep exhibited 16% higher amyloid and 29% more tau levels than those who had early REM sleep. Furthermore, they showed a 39% decrease in a beneficial protein known as brain derived neurotrophic factor (BDNF), which is diminished in Alzheimer’s patients.
“Further studies should investigate the impacts of specific medications that affect sleep patterns, as these might alter the progression of the disease,” Leng stated.
Melatonin can enhance REM sleep, and research in mice indicates that it may reduce the buildup of tau and amyloid proteins. Additionally, some medications that treat insomnia by inhibiting a compound that suppresses REM sleep have also been shown to lower tau and amyloid levels.
Individuals concerned about their Alzheimer’s risk should adopt healthy sleep habits that promote the transition from light sleep to REM sleep. “This includes managing issues like sleep apnea and reducing alcohol intake, as both can disrupt a healthy sleep cycle,” advised Dantao Peng, MD, from the Department of Neurology at the China-Japan Friendship Hospital in Beijing and also a senior author of the study.
“Patients taking certain antidepressants and sedatives that hinder REM sleep should voice their concerns to their doctor, particularly if they are worried about Alzheimer’s.”
