Scientists reveal major link between sleep and Alzheimer’s Disease

Getting enough quality sleep may do more than just help you feel rested—it could play a critical role in protecting your brain from Alzheimer’s disease.

Research suggests that disrupted sleep, particularly issues with deep sleep and rapid eye movement (REM) sleep, is linked to increased risk and progression of Alzheimer’s and related dementias. Scientists are uncovering how sleep architecture changes in aging and how these changes may be early indicators of neurodegenerative disease.

The link between sleep disturbances and Alzheimer’s has gained increasing attention as studies show that poor sleep quality is associated with higher levels of amyloid beta (Aβ) and tau proteins, both of which are hallmarks of Alzheimer’s disease.

Older adults with fragmented or insufficient sleep often show elevated Aβ in brain regions such as the hippocampus and thalamus—areas critical for memory and cognition. Even in people without symptoms, sleep disturbances may serve as an early warning sign of the disease.

Scientists have long known that sleep plays a crucial role in memory formation, learning, and brain detoxification. Slow-wave sleep (SWS), the deepest stage of non–rapid eye movement (NREM) sleep, is particularly important.

During SWS, the brain clears metabolic waste through the glymphatic system, flushing out toxins like Aβ. When SWS is disrupted, this clearance process weakens, leading to an accumulation of harmful proteins. Studies indicate that reductions in SWS are linked to increased dementia risk over time.

REM sleep, known as the dream stage, is equally important but less understood in relation to Alzheimer’s. REM sleep is involved in processing emotions and storing long-term memories. Emerging evidence suggests that people who experience less REM sleep, or take longer to reach it, may be at a higher risk of developing dementia.

A recent study conducted at the China-Japan Friendship Hospital in Beijing followed 128 participants with an average age of 70, including individuals with Alzheimer’s, mild cognitive impairment (MCI), and normal cognition. The researchers monitored the participants’ sleep overnight, tracking brain activity, heart rate, breathing, and eye movement.

They found that those who took longer to reach REM sleep were more likely to have Alzheimer’s and had higher levels of amyloid and tau proteins. On average, individuals in the delayed REM group took over 193 minutes to reach REM sleep, while those with earlier REM sleep transitions took less than 98 minutes.

The delayed REM group showed 16% more amyloid, 29% more tau, and 39% less brain-derived neurotrophic factor (BDNF), a protein essential for brain health. BDNF levels typically drop in Alzheimer’s, making this finding particularly significant.

“Delays in REM sleep disrupt the brain’s ability to consolidate memories by interfering with processes that contribute to learning and memory,” said Yue Leng, PhD, an associate professor in the Department of Psychiatry and Behavioral Sciences at UCSF. “If REM sleep is insufficient or delayed, it may increase the stress hormone cortisol, impairing the hippocampus, a structure critical for memory.”

Leng is a senior author of the paper, which appears in Alzheimer’s and Dementia: The Journal of the Alzheimer's Association.

Given the strong link between sleep quality and neurodegeneration, researchers are investigating whether sleep-modifying medications could help slow Alzheimer’s progression. Some medications, such as melatonin, can enhance REM sleep and have been shown in animal studies to reduce tau and amyloid buildup. Other drugs that treat insomnia by blocking chemicals that suppress REM sleep have demonstrated similar effects.

“Future research should study the effects of certain medications that influence sleep patterns, as these may modify disease progression,” Leng said.

People concerned about Alzheimer’s risk should consider improving sleep habits to enhance the transition from light sleep to REM sleep. Experts recommend avoiding alcohol, treating sleep apnea, and limiting the use of certain sedatives and antidepressants that reduce REM sleep.

“Patients taking medications that suppress REM sleep should discuss their concerns with their doctor if they are worried about Alzheimer’s,” said Dantao Peng, MD, of the Department of Neurology at the China-Japan Friendship Hospital.

Sleep disturbances may serve as early indicators of Alzheimer’s long before cognitive symptoms appear. By identifying changes in sleep architecture, doctors might be able to detect individuals at higher risk and intervene earlier. Research continues to explore how improving sleep could protect against Alzheimer’s or slow its progression.

“Understanding the connection between sleep and Alzheimer’s may help us discover new ways to prevent or delay the disease,” said Leng.

For now, prioritizing sleep hygiene—establishing regular sleep patterns, managing stress, and avoiding sleep-disrupting substances—may be one of the simplest steps toward maintaining cognitive health in aging.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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