Scientists have found that both the quality and amount of sleep we get can affect our risk of developing Alzheimer’s disease. Now, a new study suggests that taking longer to enter the dream phase of sleep, known as rapid eye movement (REM), may be an early sign of the disease.
REM sleep is the stage where the brain processes and stores emotionally significant memories. It happens after three non-REM stages, each progressively deeper. These four stages take about 90 minutes or more to complete, depending on age, and people typically cycle through them four or five times during a night. Older adults tend to take longer to reach REM sleep.
Dr. Yue Leng, a researcher at the UCSF Weill Institute for Neurosciences, explained how delayed REM sleep can harm memory. “The delay in REM sleep disrupts the brain’s ability to consolidate memories, interfering with learning and memory,” Leng said.
Insufficient or delayed REM sleep may also raise stress hormone levels, like cortisol, which can damage the hippocampus—a brain region essential for memory.
The study, published on January 27 in Alzheimer’s & Dementia, involved 128 participants from the neurology unit of the China-Japan Friendship Hospital in Beijing. Their average age was 70, and they were divided into three groups: those with Alzheimer’s, those with mild cognitive impairment (MCI, often a precursor to Alzheimer’s), and those with normal cognition.
Participants spent a night in a clinic, where researchers measured brain activity, eye movement, heart rate, and breathing during sleep. While fitness trackers can capture some of this data, the clinic setup provided more accurate information.
The researchers classified participants into two groups based on how long it took them to enter REM sleep. The “early” group reached REM in less than 98 minutes, while the “late” group took over 193 minutes.
The results showed that people with Alzheimer’s were more likely to experience delayed REM sleep. These individuals also had higher levels of amyloid and tau, two toxic proteins associated with the disease.
On average, those with delayed REM sleep had 16% more amyloid and 29% more tau than those with earlier REM sleep. Additionally, they had lower levels of a beneficial protein called brain-derived neurotrophic factor (BDNF), which supports brain health and memory.
The findings suggest that sleep disruptions, particularly in the REM phase, may contribute to Alzheimer’s progression. Dr. Leng emphasized the need for future studies on how medications that influence sleep patterns could modify disease progression.
For instance, melatonin, a hormone that promotes REM sleep, has shown promise in reducing amyloid and tau buildup in mice. Other drugs used to treat insomnia by blocking chemicals that suppress REM sleep have also been linked to lower levels of these toxic proteins.
People concerned about their Alzheimer’s risk can take steps to improve their sleep quality. Healthy sleep habits, such as treating conditions like sleep apnea and avoiding heavy alcohol consumption, can help maintain a regular sleep cycle and support the transition to REM sleep.
Additionally, individuals taking medications like antidepressants or sedatives that may interfere with REM sleep should consult their doctors if they are worried about potential risks.
Dr. Dantao Peng, a co-author of the study, highlighted the importance of these preventive measures. “By addressing sleep issues and adopting healthy sleep practices, people may reduce their risk of Alzheimer’s or delay its onset,” Peng said.
This research underscores the vital connection between sleep and brain health, showing how delayed REM sleep could serve as an early warning sign for Alzheimer’s. It also opens the door to potential treatments that focus on improving sleep patterns to slow disease progression.
If you care about Alzheimer’s, please read studies about Vitamin D deficiency linked to Alzheimer’s, vascular dementia, and Oral cannabis extract may help reduce Alzheimer’s symptoms.
For more information about brain health, please see recent studies about Vitamin B9 deficiency linked to higher dementia risk, and results showing flavonoid-rich foods could improve survival in Parkinson’s disease.
The research findings can be found in Alzheimer’s & Dementia.
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