Delayed REM Sleep Could Be The First Sign Of Alzheimer’s You Can't Ignore

Laying in bed, the mind is filled with endless thoughts—those of regrets, of worry, and everything in between. It is a familiar struggle, that especially when sleep seems to be very far away. The longer these thoughts run, it becomes more difficult to transition into deep sleep. Usually, deep sleep or REM begins around 90 minutes after falling asleep, cycling through several times in a night.

It is well known that the key to a healthy body is sleep, which keeps our brains working properly too. However, many overlook the profound impact it has on our cognitive functions, particularly as we age, particularly in timing when entering into REM sleep-the dream phase-that recent studies showed is significantly disrupted in early AD. Recent studies have suggests that a delay in reaching REM sleep may be a subtle yet crucial indicator of Alzheimer’s, providing a potential early warning system before more overt symptoms manifest. In this article, we explore the relationship between REM sleep and Alzheimer’s, examining how this connection could redefine early detection and preventative strategies.

Why is REM Sleep Important?

The REM sleep, also known as the "dream phase," is a crucial part of the sleep cycle in which our brains polish memories in our minds, with an emphasis on more emotionally charged ones. It arises after a succession of non-REM stages, each one deeper than the one before it. Usually, an individual's sleep cycle lasts about 90 minutes, cycling through four cycles throughout the night. Whereas younger people generally experience quick and seamless entry to REM sleep, this tends to be much later and disrupted during the process with advancing age. Many ascribe such changes in older people as effects of typical aging; instead, however, some researchers propose that it indicates early onset Alzheimer's disease in delayed REM sleep.

During deep sleep, the brain performs crucial functions to support overall health. These restorative processes are essential for optimal physical and cognitive well-being:

• Processes information for memory consolidation and learning
• Regenerates cells for tissue and organ repair
• Restores energy for physical and mental activities
• Increases blood supply to muscles for recovery
• Promotes growth and repair of tissues and bones
• Strengthens the immune system, enhancing defense against illnesses

How Delayed REM Sleep and Alzheimer's Connect?

A study published in Alzheimer's & Dementia examined at how long it takes for people to get into REM sleep and the association with biomarkers of Alzheimer's disease. The study only included participants older than 50 years and discovered that a long latency to get into REM sleep, known as REM latency or REML, was associated with higher levels of amyloid-beta (Aβ) plaques and tau proteins in the brain, which are key markers of Alzheimer's pathology. These markers usually start building up long before clinical manifestations of Alzheimer's, indicating that loss of REM sleep may be one of the first signs of neurodegeneration.

Participants with long REM latency had higher levels of p-tau181, a protein associated with neurodegenerative diseases, and lower levels of BDNF, a protein crucial for brain health. These results were significant even after controlling for several confounding factors, suggesting that REM latency may be a useful biomarker for risk of Alzheimer's.

How Delayed REM Sleep Affects the Brain Function?

The transition of the brain from NREM into REM sleep is pivotal, not just a time for vivid dreaming but for processing and storing memories. REM sleep is one of the phases needed for emotional regulation and consolidation of memory, which are crucial aspects of cognition. Failure to enter into REM sleep on schedule can interfere with such processes, causing problems in memory recall over a period of time. This could also be due to REM sleep behaviour disorder which is a parasomnia characterized by dream-enactment behaviors that occur when REM sleep atonia is lost.

The study further pointed out that altered deep sleep, or slow-wave sleep (SWS), was correlated with Alzheimer's biomarkers. SWS is the deepest phase of sleep and is most crucial for rehabilitation of the body and the brain; it's very pivotal to memory formation. The progression to dementia has shown an increased risk when slow-wave sleep is decreased. It is thus evident that both deep sleep and REM play a role in maintaining cognitive health well into old age.

Also Read: Overthinking Before Bed? Try Cognitive Shuffling To Silence Your Thoughts For Better Sleep

Can Slow-Wave Sleep be the Body's Defense Against Alzheimer's?

While slowing REM sleep might be a concern related to Alzheimer's disease, the slowing of slow-wave sleep needs to be taken into consideration. During SWS, the brain clears away metabolic waste products, such as amyloid-beta, through a glymphatic clearance process. Disruptions in this process, due to insufficient SWS, may allow these toxic proteins to accumulate and foster the development of Alzheimer's. Though the association between reduced SWS and the risk of Alzheimer's has been well studied, interest in the effects of REM sleep latency as a more direct biomarker has garnered much interest.

Tips For Better Sleep

Even though research is ongoing about the link between sleep disorders and Alzheimer's, experts have already agreed that good sleep hygiene could reduce some risk factors. For those worried about Alzheimer's, improving their sleep quality especially during the smooth transition to REM sleep is an important step to safeguarding their brain health. Here are some simple strategies that help improve the quality of sleep:

• Avoid caffeine, alcohol, and other stimulants close to bedtime because it will interfere with your ability to fall asleep as well as go into REM sleep.
• Make sure your sleep environment is conducive to rest—ideal conditions are dark, quiet, and cool. A comfortable mattress and pillows help you stay longer in deeper sleep stages.
• Conditions like sleep apnea, which interrupt breathing during sleep, can significantly delay REM sleep. Seeking treatment for sleep apnea can improve the quality of your sleep and reduce your risk of cognitive decline.
• Engaging in physical activity earlier in the day promotes better sleep quality at night. It can help regulate the body’s circadian rhythm, ensuring a smoother progression into REM sleep.
• This habit of going to bed and waking up at the same time daily helps to support the body's natural sleep-wake cycle. Consistency is the key in achieving deep and restorative sleep.

A revolution may be brought by the ever-increasing number of studies associating sleep disturbances, especially delayed REM sleep, with Alzheimer's risk. In that case, further studies might indeed confirm that attempts to modify the latency of REM sleep may diminish the risk for Alzheimer's; this would set the stage for new therapeutic methods aimed at modifying sleep quality for the prevention of Alzheimer's.

As science comes to know more about the intricate relationships that exist between sleep and Alzheimer's disease, it's evident that sleep isn't just a period of inactivity; rather, it's essential in keeping the brain healthy. However, as more evidence has been revealed to date regarding the effects of delayed REM sleep, it still calls for additional studies to provide more insight on how this delays in REM could potentially affect someone with Alzheimer's disease. If a person wishes to protect his cognitive function at older ages, nothing is perhaps stronger than this sleeping habit for protecting against such a devastating disorder as Alzheimer's.

Association of rapid eye movement sleep latency with multimodal biomarkers of Alzheimer’s disease. Alzheimer’s & Dementia. 2025