Struggling to sleep linked to dementia risk in new study
A new scientific study has uncovered a potential connection between poor sleep quality and a heightened risk of developing Alzheimer’s disease, one of the most common forms of dementia.
Researchers have found that individuals who struggle to enter REM sleep, the critical stage associated with dreaming, may face a greater likelihood of cognitive decline, SurreyLive reports. REM, or Rapid Eye Movement, is the deepest and most restorative phase of sleep.
It plays a vital role in processing memories and supporting overall brain health. According to the research, older adults who find it difficult to reach this essential stage of sleep may be exhibiting an early warning sign of Alzheimer’s.
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A new study published in The Journal of Alzheimer’s and Dementia has found that delays in reaching REM sleep, the fourth and most restorative phase of the sleep cycle, could impair the brain’s ability to form solid memories and elevate stress levels.
Researchers highlighted that REM sleep, typically occurring in 90-minute cycles during a full night’s rest, is essential for consolidating memories and supporting cognitive function.
Dr Yue Leng, senior author of the study and a researcher at the UCSF Weill Institute for Neurosciences, explained: “The delay in REM sleep disrupts the brain's ability to consolidate memories by interfering with the process that contributes to learning and memory.”
Dr Leng further elaborated on the impact of disrupted REM sleep, adding: “If it is insufficient or delayed, it may increase the stress hormone cortisol. This can impair the brain's hippocampus, a critical structure for memory consolidation.”
Researchers from the China-Japan Friendship Hospital in Beijing conducted a study to explore the connection between REM sleep and cognitive decline, inviting 128 participants aged over 70 to stay overnight in their sleep clinic. Among them, one-third had mild cognitive impairments, a common precursor to Alzheimer’s disease, half were already diagnosed with Alzheimer’s, and the remainder had normal cognitive function.
During their overnight stay, participants' brain activity was closely monitored, with scientists tracking brainwaves, eye movements, breathing patterns, and heart rates. The participants were then divided into two groups based on how quickly they entered the REM sleep phase, those who transitioned to REM the fastest and those who took the longest.
The study revealed stark differences between the two groups when it came to reaching REM sleep. Those who transitioned to this critical stage the quickest typically took around 98 minutes, while participants with poorer-quality sleep took over three hours (198 minutes) to achieve the same.
Notably, individuals diagnosed with Alzheimer’s were predominantly in the latter group, which also exhibited higher levels of proteins linked to dementia.
Participants with delayed REM sleep were found to have significantly elevated levels of amyloid (16%) and tau (29%), proteins strongly associated with Alzheimer’s and other forms of dementia, compared to their counterparts. These findings contribute to a growing body of research highlighting the impact of sleep on dementia risk.
Dr Leng added: "Future research should study the effects of certain medications that influence sleep patterns, as these may modify disease progression."
Several studies have shown that treatments for insomnia, which help individuals reach REM sleep more effectively, can also reduce the levels of tau and amyloid proteins in the brain.
This discovery offers hope that improving sleep quality through targeted treatments may not only enhance rest but also lower the risk of developing dementia.
Neurologist Dr Dantao Peng, who was a senior co-author of the study said: "This includes treating conditions like sleep apnea and avoiding heavy drinking, since both can interfere with a healthy sleep cycle.
"Patients taking certain antidepressants and sedatives that reduce REM sleep should discuss their concerns with their doctor, if they are worried about Alzheimer's."
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