January 30, 2025, 4:17 pm | Read time: 4 minutes
It is well known that sleep disorders can be an early sign of Alzheimer’s disease. However, this is an umbrella term that encompasses various sleep problems. Research is constantly providing new, in-depth findings in this context. According to a recent study, particular attention is being paid to a conspicuous sleep pattern. Find out more below.
Sleep disorders are broad and, therefore, cannot be clearly assigned to specific diseases. They also occur in Alzheimer’s disease, the most common form of dementia1 Researchers are trying to better understand their characteristics so that they can be clearly identified as signs of the neurodegenerative disease. It is well known that early detection and treatment of Alzheimer’s is important in order to best halt the progression of the disease. A team of Chinese and US researchers has now discovered a link between delayed entry into a specific sleep phase, REM sleep, and the likelihood of developing Alzheimer’s disease2
Overview
Study on the Link Between REM Sleep and Alzheimer’s Disease
REM sleep, an acronym for “Rapid Eye Movement,” plays a central role in mental health. This is why brain researchers are investigating REM sleep behavior disorders, which are considered a risk factor for the development of Parkinson’s disease, for example.3 Rapid eye movements during REM sleep indicate a high level of brain activity. In this sleep phase, the brain stores important information and sorts out unimportant information. It is of great importance for the consolidation of content in long-term memory.
Normally, the first REM sleep occurs around 90 minutes after falling asleep. But what about Alzheimer’s patients?
Details of the Study
The study included 128 participants, both male and female, with an average age of 70. 64 of them had already been diagnosed with Alzheimer’s disease, and 41 of them had mild cognitive impairment. 23 participants had no cognitive impairment.
All study participants spent one night in the sleep laboratory. During sleep, the researchers monitored their brain activity, eye movements, heart rate, and breathing. After this part of the study, the team, led by senior author Yue Leng, divided the participants into two groups. The first group consisted of participants who entered REM sleep relatively early (on average, 98 minutes after falling asleep). The subjects in the second group did not enter the REM sleep phase until more than 193 minutes after falling asleep.
Delayed REM Sleep – More Evidence for Alzheimer’s Disease
Further analysis revealed that the study participants with delayed REM sleep had higher concentrations of the proteins amyloid and tau in the brain, which are typical for Alzheimer’s disease. In contrast, the presence of the growth factor BDNF – this protein is important for memory function and is often reduced in Alzheimer’s patients – was lower.
Significance of the Results
The observations suggest that delayed REM sleep could be both an early sign of Alzheimer’s and a risk factor for the disease. It could, therefore, be useful to investigate the effects of certain medications on their influence on the sleep patterns of those taking them, for example, according to Leng in a press release4
Melatonin can promote REM sleep, as further explained in the publication. Studies on mice have shown that taking the so-called sleep hormone can reduce the accumulation of tau and amyloid in the brain. Similarly, medications used to treat sleep disorders have also demonstrated comparable effects.
Important: This information should not be interpreted as an endorsement for the unauthorized use of sleeping pills! Sleep medication has side effects and can quickly lead to addiction. Conversely, it may be beneficial to reevaluate habits known to negatively affect sleep or REM sleep. This applies, for example, to the consumption of alcohol.
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Limitations of the Study
In general, the limitations of the study should be pointed out. It is a cross-sectional study and was therefore conducted at a specific point in time. As such, it is not possible to infer trends over time. In addition, the number of participants was relatively small. Furthermore, the researchers acknowledge the possibility that the markers used, specifically p-tau181 instead of p-tau217, might not be sensitive enough to identify all early indicators of the disease. They also concede that any ambient noise and disturbances in the sleep laboratory could have influenced the results.