Experts are interested in studying how sleep affects Alzheimer’s. According to one study, taking longer to achieve the rapid eye movement (REM) stage of sleep is linked to Alzheimer’s biomarkers. The study implies that the delay in reaching REM could assist in detecting the disease and related dementias, or it could be a risk factor for these disorders.
Sleep is vital for physical and mental health. Researchers are trying to figure out how sleep could influence or be impacted by illnesses like dementia.
A recent study investigated the connection between Alzheimer’s disease and the amount of time it takes to reach the rapid eye movement (REM) stage of sleep. The study published in Alzheimer’s & Dementia discovered that taking longer to enter REM sleep was connected with major plasma biomarkers linked to Alzheimer’s disease [1].
Taking longer to enter the dreaming phase, often known as rapid eye movement (REM) sleep, can be an early symptom of Alzheimer’s, offering up new avenues for diagnosing and treating the debilitating disorder before it progresses.
The Connection Between REM Sleep and Alzheimer’s
The researchers aimed to investigate the timing of REM sleep and its connection with Alzheimer’s and other dementias. It is a stage of the sleep cycle where people experience vivid dreams. REM sleep facilitates information processing and consolidation.
When someone falls asleep, the time it takes them to enter REM for the first time is known as REM latency (REML).
The researchers looked at REM sleep for this study and identified several biomarkers linked to Alzheimer’s and related dementias.
There were 128 participants fifty years of age or older in this study. Of the participants, forty-one had mild cognitive impairment, sixty-four had Alzheimer’s, and the remaining people had normal cognition.
Apart from Alzheimer’s, researchers did not include people with Parkinson’s disease or other neurodegenerative disorders. Other exclusion criteria included the use of antipsychotic medications or movement disorders related to sleep.
Researchers collected information about participants’ medical histories. All individuals underwent cerebral MRIs, bloodwork, and a battery of cognitive tests before the study started.
The participants engaged in polysomnography, an overnight sleep study that can analyze brain waves and other physiological processes like breathing and eye movement as you sleep. Researchers were able to determine the exact moment that participants went into REM sleep.
PET scans were performed on participants to assess amyloid beta levels, which can suggest Alzheimer’s. Researchers also investigated the levels of three plasma biomarkers:
- Increases in neurofilament light (NfL) may suggest neurodegeneration.
- Increases in plasma phosphorylated tau at threonine 181 (p-tau 181) may imply Alzheimer’s.
- Declines in plasma brain-derived neurotrophic factor (BDNF) levels may also suggest Alzheimer’s.
Additionally, researchers performed statistical analyses, adjusting for variables such as diabetes mellitus, sex, and body mass index. The study also considered APOE ε4 status, a gene linked to an increased risk of Alzheimer’s.
Study Findings: How Delayed REM Sleep Impacts the Brain
According to the study’s findings, individuals with the longest REML had lower levels of plasma BDNF and higher levels of amyloid beta and p-tau181 than those with the shortest REML. Participants’ cognitive status or APOE ε4 status had no impact on the outcomes.
The association between amyloid beta and plasma brain-derived neurotrophic factor, a protein involved in the formation of brain cells, was still significant even after controlling the possibility of false positive results. This shows a notable connection between these two factors, which may be crucial for comprehending Alzheimer’s disease.
Furthermore, higher levels of p-tau181, a protein linked to specific neurological disorders, including Alzheimer’s, were associated with less REM and deep sleep (or slow-wave sleep). Slow-wave sleep is the most restful stage of sleep. However, this link did not stay significant when accounting for the risk of false results.
According to study author Yue Leng, PhD, associate professor at the Department of Psychiatry and Behavioral Sciences, Bakar Computational Health Sciences Institute (BCHSI), University of California, San Francisco, REM sleep, particularly the time it takes to enter REM sleep, may be crucial for Alzheimer’s. Previous research has mostly overlooked this sleep parameter [2].
He added that REM sleep latency may be a marker and aid in the early diagnosis of Alzheimer’s. However, it is unclear whether the association is causal. If it is causal, further investigation is required to understand the biological basis of REM sleep delay and its consequences for Alzheimer’s.
What are the Limitations of the Study?
There are some limitations to this research. First, the study cannot prove that delayed REM sleep causes Alzheimer’s. It is also unable to specify the direction of the associations it found because it was cross-sectional.
It also had a relatively small number of participants, all of whom were Han Chinese and older than fifty. Additionally, each diagnosis group had a small number of participants, which would have reduced the actual statistical power required to compare associations by cognitive diagnoses.
Although people with Alzheimer’s disease or mild cognitive impairment took longer to enter REM sleep than participants without cognitive impairment, the findings were not statistically significant.
Larger sample sizes, more diversity, and involving younger people could all be advantageous for future studies.
Additionally, rather than focusing on p-tau217, researchers chose to study plasma p-tau 181. They point out that p-tau217 is more accurate in forecasting Alzheimer’s progression.
The sleep study’s setting may have caused environmental disturbances, affecting the accuracy of sleep measurements. Furthermore, because the sleep research only lasted one night, it may not accurately represent the subjects’ usual sleep patterns. Researchers also point out that a large number of participants did not have a slow-wave sleep percentage, which may have an impact on the broad application of the findings.
Alzheimer’s Research Association is a non-profit organization dedicated to helping caregivers of Alzheimer’s disease and dementia. We provide the latest information and news about the illness and helpful tips to help caregivers cope with their daily caregiving challenges. We realize the most important thing that a caregiver needs is financial assistance. Therefore, we provide grants to caregivers to ease their financial burden. Caregivers can apply for grants here: Alzheimer’s Grant Application.
You can also help caregivers in their endeavor by donating as much as possible: Donation To Alzheimer’s Research Associations.
References
- Jin, J., Chen, J., Cavaillès, C., Yaffe, K., Winer, J., Stankeviciute, L., Lucey, B.P., Zhou, X., Gao, S., Peng, D. and Leng, Y., 2025. Association of rapid eye movement sleep latency with multimodal biomarkers of Alzheimer’s disease. Alzheimer’s & Dementia, p.e14495.
- Freeborn, J. Taking longer to get to REM sleep could indicate Alzheimer’s disease. https://www.medicalnewstoday.com/articles/delayed-rem-sleep-could-be-an-early-sign-of-alzheimers. Published Online: 29th January, 2025. Accessed: 7th March, 2025.
- Nield, D. Delayed REM Sleep May Be an Early Signal of Alzheimer’s, Study Finds. Science Alert. https://www.sciencealert.com/delayed-rem-sleep-may-be-an-early-signal-of-alzheimers-study-finds. Published Online: 31st January, 2025. Accessed: 7th March, 2025.
- Leigh, S. Delayed REM Sleep Could Be an Early Sign of Alzheimer’s. University of California San Francisco (UCSF). https://www.ucsf.edu/news/2025/01/429346/delayed-rem-sleep-could-be-early-sign-alzheimers. Published Online: 27th January, 2025. Accessed: 7th March, 2025.
