Roundup: Disrupted ‘Deep Sleep’ May Be Linked to Early Alzheimer’s-Related Memory Issues; and More News

Deep Sleep Disruptions May Signal Early Alzheimer’s-Related Brain Changes, Study Finds

A new study suggests that changes or disruptions in “deep sleep” may be linked to the buildup of tau, a protein associated with Alzheimer’s disease. The findings help explain why memory often declines with age — and point to a possible connection between sleep quality and memory formation.

Most people know about REM (rapid eye movement) sleep, the stage associated with vivid dreaming. However, another stage called non-REM sleep, or deep sleep, is equally important for brain function.

The Role of Deep Sleep in Memory

During deep non-REM sleep, large groups of brain cells briefly and synchronously switch off and back on. These coordinated electrical patterns create what scientists call “slow waves.” Researchers believe these waves help the brain strengthen and store memories formed during the day, a process known as memory consolidation.

Memory consolidation is especially important for episodic memory, which involves recalling personal experiences and events, such as where you parked your car, what you ate for lunch, or memories from childhood.

Tau Protein May Disrupt Sleep Signals

The new study by researchers at UC Berkeley found that as tau protein accumulates in the brain, these slow waves become less organized. Tau is a naturally occurring protein, but abnormal buildup is considered a hallmark of Alzheimer’s disease.

Researchers discovered that tau accumulation in the frontal cortex, the area near the front of the brain involved in decision-making, attention, and memory-related processes, was associated with shorter and less coordinated slow waves during deep sleep.

Instead of traveling smoothly across large areas of the brain, the waves became fragmented and isolated. The researchers referred to these weakened signals as “lonely waves.”

Comparing Younger and Older Adults

To investigate the connection, scientists used electroencephalograms (EEGs), which record electrical activity in the brain, to monitor sleep in healthy young adults and older adults.

The results showed a clear difference. In participants in their early 20s, slow waves traveled across relatively large regions of the brain during deep sleep. In adults between their mid-60s and mid-70s, the waves generally covered shorter distances and appeared less synchronized.

Researchers also used positron emission tomography (PET) scans, an imaging technique that uses small amounts of radioactive tracers to measure biological activity in the body. These scans revealed that higher levels of tau in the frontal cortex were associated with greater disruption of slow-wave activity.

Sleep Changes Linked to Memory Performance

The researchers also tested participants’ ability to retain new information overnight. Participants learned word pairs before sleep and were tested the next day.

Those with more fragmented slow waves remembered fewer of the word associations. The findings suggest that disrupted deep-sleep activity may interfere with the brain’s ability to preserve new memories.

In a group of participants followed for several years, increases in frontal cortex tau were associated with worsening slow-wave coordination and reduced overnight memory retention over time.

Not Proof of Alzheimer’s, but an Important Clue

Importantly, the older adults in the study did not have Alzheimer’s disease. Their memory performance generally remained within the normal range for their age.

However, the findings suggest that changes linked to Alzheimer’s may begin long before noticeable symptoms develop. Researchers also confirmed similar patterns using spinal fluid samples, finding that people with more disrupted slow waves tended to have higher levels of Alzheimer’s-related proteins.

The study does not prove that tau buildup causes memory loss or sleep disruption. Instead, it shows a strong relationship between these factors and suggests they may be connected.

Drinking Hotter-Than-Normal Tea or Coffee Linked to Risk of Esophageal Cancer

A major new study of nearly 1 million adults in the United Kingdom (UK) has found that people who prefer their tea and coffee "very hot" face a significantly higher risk of developing a specific type of cancer in the food pipe (esophagus), known as squamous cell carcinoma (SCC). Drinking six or more hot drinks a day also raised the risk, independent of temperature.

The study followed participants in two long-running UK health studies — the Million Women Study and UK Biobank — for over a decade. Researchers asked people how they liked their hot drinks (warm, hot, or very hot) and how many cups of tea and coffee they drank daily, then tracked who later developed esophageal cancer.

There are two main types of esophageal cancer with different causes: squamous cell carcinoma (SCC), which starts in the flat cells lining the upper part of the food pipe, and adenocarcinoma (AC), which typically develops near the stomach and is more closely tied to acid reflux and obesity.

The results were striking for SCC specifically. People who preferred their drinks "very hot" were about three times more likely to develop SCC than those who preferred "warm" drinks. Drinking six or more hot beverages daily raised SCC risk by about 71 percent, even after accounting for temperature preference. Neither temperature nor frequency was meaningfully linked to adenocarcinoma risk.

Why Temperature — Not the Drink Itself — Seems to Matter

Notably, it didn't matter whether people drank mostly tea or mostly coffee, or whether they added milk (which cools a drink down). This suggests it's the heat itself, not caffeine or other ingredients, driving the risk — likely by repeatedly injuring the lining of the food pipe, which over time may encourage abnormal, cancerous cell growth.

This lines up with earlier research from Iran, China, and Africa, which found similar patterns, and with animal studies showing very hot liquids can damage esophageal tissue.

Putting the Risk in Perspective

Esophageal SCC remains relatively uncommon. The researchers estimate that if everyone who drinks their beverages "very hot" switched to "hot" instead, about 14 percent of SCC cases — roughly 440 cases a year in the UK — could be prevented. That's a modest absolute number nationally, but a meaningful and easy behavior change for individuals.

The researchers suggest a simple precaution: let your drink cool slightly before sipping, and consider moderating how many hot drinks you have each day. Since the drinks in this study cooled to a "hot" rather than "very hot" temperature, no extreme changes are being recommended — just avoiding drinking straight off the boil.

CDC Report: Nearly 3 in 4 U.S. Adults Experience Fatigue

Feeling tired is common among American adults, but for millions, fatigue is a frequent problem that can affect work, social activities and everyday functioning.

A new report from the Centers for Disease Control and Prevention’s National Center for Health Statistics found that 71.5 percent of U.S. adults experienced fatigue at least some days during a three-month period in 2024. About 16.6 percent — roughly one in six adults — reported frequent fatigue, defined as feeling very tired or exhausted most days or every day.

The findings come from the 2024 National Health Interview Survey, a nationally representative survey of adults living in U.S. households.

Fatigue Is Different From Sleepiness

Fatigue generally refers to physical or mental tiredness or exhaustion that does not improve with additional sleep or rest. That differs from sleepiness, which involves feeling drowsy or having difficulty staying awake.

Fatigue is a common concern in primary care and can occur with various medical conditions, although sometimes there is no identified medical cause. The CDC report examined fatigue symptoms rather than attempting to determine what caused them.

Among adults surveyed, 54.9 percent experienced fatigue some days, 10.7 percent experienced it most days and 5.9 percent experienced it every day. Another 28.5 percent reported no fatigue during the previous three months.

Women and Younger Adults Reported More Frequent Fatigue

Frequent fatigue was reported by 20 percent of women compared with 13 percent of men.

The prevalence also decreased with age. Frequent fatigue affected 19.5 percent of adults ages 18 to 34, compared with 17.4 percent of those ages 35 to 49, 16 percent of those ages 50 to 64 and 12.9 percent of adults 65 and older.

Differences also emerged by income and geography. Frequent fatigue was reported by 21.7 percent of adults with family incomes below the federal poverty level, compared with 13.6 percent among those with incomes at least four times the poverty level.

Rates were higher in the South and Midwest than in the West and Northeast and increased as communities became less urban.

Fatigue Often Comes With Other Difficulties

Among adults with frequent fatigue, 20.2 percent said their fatigue lasted all day, while 34.5 percent said it lasted most of the day. Nearly 39 percent described their fatigue as “a lot.”

Frequent fatigue also commonly occurred alongside other difficulties. About 69.6 percent reported symptoms of anxiety, 46.1 percent reported difficulty with cognition — such as remembering or concentrating — and 45 percent reported symptoms of depression. About half reported difficulties in at least three areas of functioning.

An Impact on Work and Social Life

The findings suggest that frequent fatigue can accompany substantial limitations in daily life.

Among adults with frequent fatigue, 36 percent reported being limited in the kind or amount of work they could perform, compared with 15.3 percent of adults without frequent fatigue. Overall, 29 percent of those with frequent fatigue reported some level of difficulty participating in social activities.

The researchers cautioned that the study cannot establish cause and effect. Because the survey captured information at one point in time, it cannot determine whether fatigue contributed to other difficulties, whether underlying health problems caused both, or whether several factors were involved.

Still, the findings provide a broad picture of how common fatigue is among U.S. adults — and how frequently persistent exhaustion overlaps with challenges involving physical, mental and social functioning.