Watchman News

Cancer is often talked about as though it strikes at random — a matter of bad luck or inherited genes. But a sweeping new global analysis suggests otherwise. Published in Nature Medicine, the study from the World Health Organization and its International Agency for Research on Cancer (IARC) examined how much of the world’s cancer burden traces back to causes that are, in principle, avoidable.1

The findings reframe cancer less as an inevitability and more as a condition shaped by everyday exposures — what you breathe, drink, eat, and absorb over decades. The researchers’ conclusions carry enormous practical weight, because if a risk factor can be identified and measured, it can also be reduced. What follows is a breakdown of exactly how the analysis reached its conclusions, which exposures drive the most harm and what you can do to act on the data.

Global Data Show Where Cancer Risk Starts

For the study, researchers used data covering 36 cancer types across 185 countries and evaluated 30 risk factors that people and governments can address. They applied a statistical method that estimates how many cases would not occur if a risk factor were removed to determine how much of the global cancer burden traces back to specific exposures. This was not a small regional snapshot. It was a global audit of preventable cancer.

• More than one-third of new cancers were tied to modifiable causes — The investigators found that 7.1 million of 18.7 million new cancer cases in 2022 — 37.8% — were attributable to preventable risk factors. Among men, 45.4% of new cases were linked to these exposures, compared to 29.7% in women. That gap alone tells you something powerful: exposure patterns matter.
If nearly half of cancers in men connect to modifiable behaviors or environments, then your daily exposures shape long-term outcomes.
• Smoking dominated the preventable cancer landscape — Tobacco smoking accounted for 15.1% of all new cancer cases globally, making it the single largest contributor identified in the study. In men, smoking was responsible for an estimated 23% of new cancer cases, while in women it accounted for 6%.
This means smoking’s effect in men was nearly four times higher than in women. The numbers reflect cumulative DNA damage caused by carcinogens in tobacco smoke that trigger mutations and drive tumor formation. If smoking were removed, roughly 15% of global cancer cases would not occur.
• Infections and alcohol formed the next major tier of risk — Infections contributed 10.2% of global cancer cases, and alcohol consumption accounted for 3.2%. Among women, infections were responsible for 11% of new cancer cases — higher than smoking in that group.
That figure underscores how viruses and bacteria such as human papilloma virus (HPV) and Helicobacter pylori (H. pylori) reshape cancer risk through chronic inflammation and long-term cellular damage. Alcohol, by contrast, increases exposure to acetaldehyde, a toxic breakdown product that injures DNA and interferes with repair systems.
• Three cancer types made up nearly half of preventable cases — Lung, stomach and cervical cancers represented nearly 50% of preventable cancer cases globally. Lung cancer was linked primarily to smoking and air pollution. Stomach cancer largely traced back to H. pylori infection.
Cervical cancer was linked to HPV, but it’s important to note that, in most cases, only long-term, untreated HPV infections will trigger cervical cancer, and these are typically easily caught and treated with regular Pap smears.
• Regional differences exposed how environment shapes risk — Preventable cancers ranged from 24.6% to 38.2% in women depending on region and from 28.1% to 57.2% in men. East Asia showed the highest preventable cancer burden among men at 57%, while Latin America and the Caribbean showed the lowest at 28%.2

These differences reflect varying exposure to tobacco, infections, occupational hazards, and environmental pollutants. Where you live influences what you inhale, consume and encounter. The researchers concluded that “strengthening efforts to reduce modifiable exposures remains central to global cancer prevention.”

How to Reduce Your Preventable Cancer Risk

The data show that cancer risk is closely associated with what you inhale, drink, absorb, and store in your tissues. That means your strategy need to begin at the source. Focus first on removing metabolic stressors that damage mitochondria and drive inflammation, because cellular energy failure creates the environment where disease spreads. When you correct that terrain, you shift your long-term trajectory in a measurable way. Here are five steps you can take.

1. Shift your macronutrient balance toward carbs and away from excess fat — If your fat intake approaches 60% of daily calories, you force your body to rely heavily on fat for fuel. That metabolic state drives dysfunction and fuels disease spread, including cancer.3 Keep your fat intake between 30% and 40% of daily calories and aim for about 250 grams of healthy carbohydrates daily.
Build your meals around whole fruit, cooked root vegetables, white rice, healthy protein, and small amounts of well-tolerated whole grains if your gut handles them well. If your digestion struggles, begin with easier-to-digest carbohydrates like fruit and white rice and progress slowly. Your goal is steady glucose use, strong mitochondrial function and lower inflammatory signaling — chemical alarm signals that, when chronically elevated, create conditions favorable to tumor growth.

2. Eliminate vegetable oils and drive linoleic acid (LA) under 5 grams per day — The problem is not just fat. It’s LA, a polyunsaturated fat found in seed oils. High LA intake disrupts mitochondrial energy production, weakens your immune system’s ability to detect and destroy abnormal cells, and activates clotting factors that help tumors establish blood supply and spread.
Remove canola, corn, soybean, safflower, sunflower, and grapeseed oils from your kitchen. Replace them with grass fed butter, ghee or tallow.
For example, instead of sautéing vegetables in canola oil, cook them with ghee. Instead of store-bought salad dressing, use lemon juice and grass fed butter. Use olive oil and avocado oil sparingly, if at all, because they often contain hidden seed oils and high monounsaturated fat that stresses mitochondria.
You’re probably eating more LA than you think. When my Mercola Health Coach app launches, the Seed Oil Sleuth feature will help you track this down to the tenth of a gram. Aim for under 5 grams of LA daily, ideally under 2 grams.

3. Reduce inflammatory drivers by improving body composition and movement — Excess body fat releases inflammatory chemicals that support tumor growth. If you carry weight around your midsection, focus on restoring carbohydrate balance rather than crash dieting. Eat enough protein — about 0.8 grams per pound of ideal body weight, or 1.76 grams per kilogram — with one-third from collagen sources like bone broth.
This protects muscle mass while improving metabolic flexibility, your body’s ability to switch smoothly between burning glucose and fat for fuel. Commit to daily walking and avoid overdoing intense exercise. A sedentary body is a metabolically stagnant one — without regular movement, insulin sensitivity drops, inflammatory markers rise, and mitochondria lose their capacity to burn fuel efficiently.
At the same time, excessive high-intensity training spikes stress hormones and strains recovery. Working your way up to a one-hour brisk walk outdoors daily supports mitochondrial function, improves insulin sensitivity and reduces systemic inflammation.
If you’re starting from minimal activity, begin with 15 to 20 minutes a day and add five minutes per week. Add strength training two or three times per week, but don’t overdo intense sessions. If you feel wired, depleted or unable to recover, you’re pushing too hard. Daily movement builds resilience. Chronic overexertion breaks it down.
Making sure your vitamin D levels are optimized is also important. Multiple large-scale analyses link sufficient vitamin D to lower risk of colorectal, breast and other cancers.4

The mechanisms align with everything discussed in this article — vitamin D modulates immune function, supports your body’s ability to trigger programmed death in abnormal cells and helps regulate the inflammatory signaling that drives tumor growth. Test your blood levels twice a year and aim for 60 to 80 ng/mL (150 to 200 nmol/L).
Many people need supplemental vitamin D3, particularly during winter months or if they spend limited time outdoors. If you supplement, take it with a fat-containing meal to improve absorption, and pair it with magnesium and vitamin K2 to support proper calcium metabolism.

4. Lower chronic stress to protect metabolic function — Chronically high cortisol — your body’s main stress hormone — drives stubborn belly fat, suppresses immune function, and impairs the mitochondrial repair processes your body relies on to prevent abnormal cell growth. Lowering cortisol isn’t a luxury. It’s a metabolic intervention.
Start with slow, deep breathing several times a day and get early morning sunlight to reset your cortisol rhythm. Include healthy carbohydrates with your meals to stabilize energy and calm your nervous system.
Simple pleasures matter, too — laughter, music, time with pets, and doing something you genuinely enjoy all trigger measurable biochemical shifts that lower cortisol and signal safety to your brain. For deeper support, natural progesterone is one of the safest and most effective ways to block cortisol’s harmful effects, helping your body recover from stress overload and reestablish hormonal balance.
In addition, sleep is one of the most overlooked cancer-prevention tools. IARC classifies disrupted circadian rhythms as a probable carcinogen, and the reasons connect directly to the mechanisms discussed throughout this article — sleep deprivation impairs your body’s ability to repair damaged DNA, suppresses natural killer cells that hunt down abnormal cells and elevates the very cortisol you’re working to lower.
Prioritize seven to nine hours of uninterrupted sleep in a dark, cool room. Avoid screens for at least an hour before bed, dim lights after sunset, and keep a consistent sleep and wake time — even on weekends — to anchor your circadian rhythm.

5. Eliminate alcohol and smoking completely and remove other modifiable exposures — Alcohol acts as a metabolic poison and increases cancer burden, much like LA. When you drink, your liver converts ethanol into acetaldehyde, a toxic aldehyde that damages cell membranes and DNA. LA follows an almost identical route. As LA breaks down, it forms another toxic aldehyde called 4-hydroxynonenal (4-HNE).
Both acetaldehyde and 4-HNE are highly reactive molecules that attach themselves to proteins, phospholipids, and mitochondrial DNA, disrupting your body’s ability to generate adenosine triphosphate (ATP) — the energy currency that powers every function in your body, from heartbeat to DNA repair. Think of acetaldehyde and 4-HNE as molecular rust.
They corrode the very machinery your cells use to produce energy, leaving mitochondria damaged and inefficient. So, if you drink, stop. If you smoke, also stop. Address chronic infections where possible and limit exposure to environmental toxins like air pollution as much as possible. If you live near a busy road or in an area with poor air quality, run a HEPA air purifier in the rooms where you spend the most time, especially your bedroom.
When you walk or exercise outdoors, choose routes away from heavy traffic. Filter your drinking water with a high-quality system that removes chlorine, heavy metals, and industrial contaminants. Switch household cleaning and personal care products to versions free of synthetic fragrances, parabens, and phthalates. You don’t need to overhaul everything overnight — start with the exposures you encounter most frequently and work outward from there.

FAQs About Preventable Cancer Risk

Q: How much of cancer is actually preventable?
A: A large global analysis published in Nature Medicine found that roughly four in 10 new cancer cases worldwide are linked to modifiable risk factors.5 That means a significant share of the global cancer burden is tied to exposures such as smoking, alcohol, infections, excess body fat, and environmental pollutants rather than fate or genetics alone.

Q: What are the biggest preventable drivers of cancer?
A: Tobacco smoking ranks as the leading contributor worldwide. Infections such as HPV and H. pylori follow closely behind. Alcohol consumption also adds measurable risk. Lung, stomach, and cervical cancers account for nearly half of preventable cases globally, largely driven by these exposures.

Q: Why does body fat and metabolic health matter for cancer risk?
A: Excess body fat releases inflammatory chemicals that create a biological environment that supports tumor growth. Metabolic dysfunction also impairs mitochondrial function — your cells’ ability to produce energy efficiently. When your mitochondria can’t produce energy efficiently, your cells shift into a stressed, inflammatory state — and that’s precisely the environment where cancer cells thrive.

Q: How does diet influence cancer risk at the cellular level?
A: High intake of seed oils rich in LA and excess fat intake disrupt mitochondrial function and increase formation of toxic aldehydes that damage proteins, membranes and mitochondrial DNA. In contrast, balancing fat intake, prioritizing digestible carbohydrates and eliminating seed oils reduces metabolic stress and lowers inflammatory signaling.

Q: What practical steps reduce preventable cancer risk?
A: Stop smoking and eliminate alcohol. Remove seed oils to lower total LA intake. Maintain a balanced macronutrient profile with adequate carbohydrates and protein. Improve body composition through daily walking and moderate strength training rather than extreme dieting or overtraining. Address chronic infections and reduce exposure to environmental toxins whenever possible.

Test Your Knowledge with Today’s Quiz!
Take today’s quiz to see how much you’ve learned from yesterday’s Mercola.com article.

Which gut cell type ramps up serotonin output during a high-fat diet?

Enterochromaffin cells
Enterochromaffin cells generate most of the body’s serotonin, and high-fat diets push them into overproduction while reducing the serotonin transporter’s clearing capacity. Learn more.

Goblet cells
Paneth cells
Stem cells

Most people turn on a sound machine at bedtime because to them it brings comfort. The sound feels like an easy fix for restless nights, and the instant sense of calm makes it even more tempting to depend on night after night. But does that comforting hum actually improve your sleep — or is it secretly working against the brain repair you’re trying to achieve?

A recent study offers a wake-up call: Apparently, sound machines may lead to a noticeable drop in rapid eye movement (REM) sleep. To put it simply, the nighttime sound that seems soothing might actually be pressuring your brain to work through constant auditory input instead of repairing itself.

These findings challenge the assumption that any calming sound is automatically helpful and set the stage for a deeper look at how sound machines might be working against the very sleep quality you’re trying to protect. Before we go into the findings of the study, let’s briefly discuss how sound machines work.

A Primer on Sound Machines

Sound machines are devices designed to produce a steady stream of background noise that help “fill in” the silence of a room. Many people use them as part of a nighttime routine, especially in environments where sudden or unpredictable sounds may interfere with rest. Rather than relying on a phone app — which can introduce disruptive blue light — sound machines offer a dedicated way to create soothing audio throughout the night.

• Why does a sound machine affect your sleep quality? The answer lies in how the brain processes noise. The fact is that even when you’re at rest during deep sleep, your brain still continues to register noise all around you. Unexpected sounds such as traffic, snoring, pets moving around, or household creaks can trigger brief awakenings or shifts between sleep stages, even if you don’t fully remember waking up.

• A sound machine helps reduce the impact of these disruptions — It provides a stable auditory backdrop. The steady hum it emits smooths out the chaos of a noisy house, an anxious mind, or the unpredictable sounds of cars passing by on the street.

• Sound machines may include a variety of sound options — Some play nature sounds, like rainfall, thunderstorms, beach waves, or frogs at night. Others play white noise, which resembles static and contains all audible frequencies at equal intensity. There’s also what’s called pink noise, which is a softer, deeper static sound that resembles steady rushing water. White and pink noise, along with other types like brown and blue, are also referred to as broadband noise.1

Most research suggests that sound machines are generally safe. Even the National Sleep Foundation (NSF) recognizes that sound machines or “sound conditioners,”2 can help both adults and newborns sleep more soundly. However, if used improperly, pink noise machines may not be completely harmless.

What Does the Newest Research Actually Say About Pink Noise and Sleep?

A more recent report published in the journal Sleep provides more insight into how sound machines may be unknowingly harming your nighttime slumber. Conducted by researchers from the University of Pennsylvania Perelman School of Medicine, the study looked at how different noise conditions, including pink noise, shaped the way the brain moved through deep sleep and REM sleep during the night.3 According to an article from Science Daily:

“During a typical night, the brain cycles repeatedly through deep sleep and REM sleep. Deep sleep plays a key role in physical recovery, memory processing, and the removal of waste products from the brain. REM sleep, often referred to as dream sleep, supports emotional regulation, motor skill development, and brain growth.”4

The researchers’ goal was to understand whether the sounds many people rely on each night improve sleep architecture (the natural structure and cycling of your sleep stages) or disrupt it in ways most users never notice.

• The study followed 25 healthy adults, ages 21 to 41, in a controlled sleep laboratory — Most of them were women, and none had any sleep disorders or had previously used sound machines. For seven consecutive nights, they slept for eight hours, from 11 p.m. to 7 a.m.

• The participants were exposed to different conditions — As they slept, they were placed under varying noise conditions, such as environment noise (sounds of aircraft, cars, baby crying, and alarms), pink noise alone, a combination of environment and pink noise, and environment noise while wearing earplugs.

There were also participants who were allowed to sleep in a quiet environment without any noise exposure (the control group). The researchers used overnight polysomnography, which is considered the gold standard for sleep measurement, to capture the data. This is a comprehensive overnight test that measures brain waves, oxygen levels, heart rate, and eye movements.

• As expected, environmental noise significantly reduced deep sleep and increased nighttime awakenings — The participants exposed to this type of noise lost an average 23 minutes of “N3” deep sleep (considered the deepest and most restorative sleep stage) per night. Even if they didn’t remember waking up in the middle of their slumber, their brain activity reflected shallower, more disrupted sleep. They also felt more tired, stressed, and mentally drained the next morning.

• But what was surprising was the effect of pink noise on deep sleep — Pink noise alone, which was played at 50 dB (imagine the sound of moderate rainfall), caused a significant reduction in REM sleep — nearly 19 minutes of sleep lost per night. Over a week, that’s more than two hours of REM sleep lost.

According to the researchers’ findings, this type of noise interferes with the brain circuits that normally allow REM sleep to begin and continue, so instead of creating a restful background for sleep, it may act as a continuous stimulus that alters the brain’s ability to cycle naturally into REM. Your brain doesn’t fully “turn off” during sleep — it still monitors your environment. Pink noise may keep the auditory processing centers partially active, preventing the full transition into REM.

• Why disrupted REM sleep has a significant effect on your health — Chronic REM deprivation doesn’t just make you tired; it also impairs emotional regulation, weakens memory consolidation, and may even accelerate cognitive decline over time. Mathias Basner, M.D., Ph.D., professor of Sleep and Chronobiology in Psychiatry and the study lead author, explained:

“REM sleep is important for memory consolidation, emotional regulation, and brain development, so our findings suggest that playing pink noise and other types of broadband noise during sleep could be harmful — especially for children whose brains are still developing and who spend much more time in REM sleep than adults.”5

What’s even more damaging was when pink noise was combined with environment noise — When paired together, the effects became more pronounced. Both deep and REM sleep were significantly reduced, and participants spent about 15 additional minutes awake during the night. Notably, this increase in wakefulness did not occur with aircraft noise alone or pink noise alone.

So, Should You Ditch Your Sound Machine?

These study findings are vital, as many people today use broadband noise not just for sleep, but also as a relaxation tool throughout the day. Case in point: White noise and ambient podcasts now total about 3 million listening hours per day on Spotify. Meanwhile, the top five “white noise” videos on YouTube have collectively been viewed more than 700 million times.6 Even so, research on how broadband noise affects sleep remains limited and inconclusive.

• Consistent REM disruptions are more damaging than you think — People whose REM sleep is always disrupted have a higher risk of developing mental health issues like depression and anxiety and even Parkinson’s disease. What’s more, majority of people today, particularly adults, are sleep deprived. This means that every minute of REM sleep matters.

• Use sound machine as a tool, not a mandate — If sound machines work for you, then use them in a smart and strategic manner. Basner recommends playing it at a low volume and setting a timer instead of letting it play through the night. “I don’t want to discount that there may be something behind it, because so many people are using it,” he added.7

• Wearing earplugs is a better way to improve sleep quality — This is a simpler — and more cost-friendly — strategy to shut off disruptive noise at night. Around 16% of Americans wear earplugs during bedtime to get the restful sleep they need.8

In the featured study, earplugs restored about 72% of the deep sleep that environmental noise had taken away. That’s equivalent to nearly 17 minutes of N3 deep sleep restored. In nearly every measurement, including sleep stages, awakenings, sleep depth, and morning mood, sleeping with earplugs looked far more similar to sleep during the quiet control night than to any noise-exposed condition.

• Earplugs performed well even during repeated noise events throughout the night — Only at the loudest level tested, 65 dB (which is similar to a noisy vacuum cleaner or busy street heard from indoors), did the protective effect begin to weaken.

• Participants also found earplugs comfortable — Even though the researchers used ordinary foam earplugs for this test, the participants still reported that they slept better with them. This is notable, since comfort and usability often limit whether people stick with sleep tools long-term.

“It is likely that both comfort and sound attenuation could be further improved by using high-fidelity or even custom-fit earplugs instead, although this would have to be shown,” the researchers added.9

Are Sound Machines Safe for Babies and Kids?

During the first weeks of life, newborns spend the majority of their time sleeping — In fact, newborns are recommended to get around 14 to 17 hours of sleep per day, according to the National Sleep Foundation (NSF). This means that these young children spend significantly more time in REM sleep than adults.

• Many parents place sound machines beside their newborns’ or toddlers’ beds — They do this with the best of intentions, to help their children fall asleep and stay asleep through the night. However, based on the featured research, this habit could be doing more damage, as they are more susceptible to the possible harms of pink noise exposure.

• REM sleep loss may be more pronounced in young children — Although the study did not observe the effects of broadband noise on these age groups, the researchers still warn parents to be careful in using sound machines until there’s more conclusive research on their effects on younger brains.

“Overall, our results caution against the use of broadband noise, especially for newborns and toddlers, and indicate that we need more research in vulnerable populations, on long-term use, on the different colors of broadband noise, and on safe broadband noise levels in relation to sleep,” Basner said.10

• The volume level of the machine is also a concern — Excessively high volumes can pose risks over time. One study published in the National Library of Medicine reported that white noise played above recommended limits may negatively affect young children’s hearing and language development.11

For context, the safe noise level for hospital nurseries is around 50 decibels (dB). For adults, white noise is typically regarded as safe between 50 and 70 dB. Beyond that range, hearing protection may be necessary to reduce the risk of long-term damage.12

To summarize, below is a comparison of the different types of broadband noises made by sound machines and the recommendations based on the research findings.

Noise type
Sound profile
Effect on sleep
Recommendation

Pink noise
Softer, deeper static (like steady rainfall or rushing water)
Reduced REM sleep by ~19 minutes per night in lab settings
Use cautiously, especially for children whose brains need more REM sleep

White noise
Even static across all frequencies (like TV static or a fan)
Masks disruptive sounds but shows no clear benefit for sleep quality
Keep volume low (50 to 70 dB), use a timer, place device 3+ feet away

Brown noise
Deep, rumbling static (like thunder or strong wind)
Limited research available; effects on sleep architecture unclear
Apply same safety precautions as pink/white noise until more data exists

How to Use a Sound Machine Safely

If you’re not ready to give up your sound machine entirely, you can still minimize the risks. Here’s a practical, research-aligned setup guide you can implement tonight:

1. Use the lowest effective volume — Set your sound machine to the minimum level that still masks your specific trigger noises, like traffic or snoring. Lower loudness means less risk of disrupted sleep over time. Aim for 50 dB or below — roughly the volume of light rainfall.

2. Increase the distance from your bed — Place the device across the room, not on your nightstand. Sound pressure decreases with distance, so moving your machine even 3 to 6 feet farther from your ears significantly reduces exposure while still providing masking benefits.

3. Set a sleep timer or auto-off feature — You don’t need broadband noise running all night. Set a timer for 30 to 60 minutes — enough time to fall asleep. Once you’re in deep sleep, your brain is less sensitive to moderate environmental sounds anyway.

4. Consider earplugs as an alternative — In the featured study, simple foam earplugs restored about 72% of the deep sleep lost to environmental noise, outperforming pink noise in nearly every measurement. Try them instead of, or alongside, your sound machine.

5. Combine with physical noise control — Address noise at the source: heavy curtains, door sweeps, draft stoppers, and soft furnishings all reduce sound transmission. These passive solutions don’t carry the REM-disruption risks of continuous broadband noise.

6. Run a one-week self-experiment — If you wake up groggy despite “sleeping” seven to eight hours, try removing your sound machine for one week. Track your morning alertness, mood, and energy. If you feel more restored without it, that’s your answer.

Frequently Asked Questions (FAQs) About Sound Machines and Sleep

Q: Can pink noise disrupt rapid eye movement (REM) sleep?
A: Yes, recent controlled sleep-lab research suggests pink noise may reduce REM sleep, which is the stage associated with dreaming, memory consolidation, emotional regulation, and brain development. In laboratory conditions, participants exposed to pink noise experienced a measurable reduction in REM sleep compared to quiet conditions.

While pink noise is often marketed as calming, continuous broadband sound may act as an ongoing auditory stimulus that subtly interferes with the brain’s natural sleep cycling. The effect may be especially relevant for people already struggling with sleep quality or those who rely on noise all night at moderate volumes.

Q: What is a safe decibel level for sleep?
A: For most adults, sleep experts generally recommend keeping nighttime sound exposure around 50 decibels (dB) or lower — roughly the sound of light rainfall. Some guidance considers 50 to 70 dB acceptable for adults, but lower is better when possible. For infants and young children, caution is even more important, and volume should remain at or below nursery safety standards (around 50 dB).

Q: Are sound machines safe for babies?
A: Parents should use caution. Babies spend significantly more time in REM sleep than adults, and REM plays a critical role in brain development. Emerging research suggesting that certain types of broadband noise may reduce REM sleep raises questions about prolonged overnight use in infants and toddlers. Additionally, excessive volume may pose hearing risks over time.

Environmental fixes — such as blackout curtains, soft furnishings and white-noise alternatives at low levels — may be safer first-line options.

Q: Where should I place a sound machine in the bedroom?
A: Placement significantly affects sound exposure. For safer use, position the device across the room, not on your nightstand. Keep it at least 3 to 6 feet away from your bed or your child’s crib. Use the lowest volume that masks your triggers, and never direct the speaker toward your ears. Sound intensity drops as distance increases, so moving the machine farther away reduces the decibel level reaching your ears while still providing masking benefits.

Q: Do I need a timer or should a sound machine run all night?
A: For many people, running a sound machine all night is unnecessary. Once you fall asleep — especially after entering deeper sleep stages — your brain becomes less sensitive to moderate background sounds. Using a 30- to 60-minute timer may reduce potential REM disruption and limit prolonged noise exposure. Continuous overnight use may not provide added benefit and could increase the risk of sleep-stage interference.

Q: What’s the difference between pink, white and brown noise?
A: The “color” of noise refers to how sound frequencies are distributed:

• White noise — Equal intensity across all audible frequencies; sounds like steady static or a fan.
• Pink noise — Emphasizes lower frequencies; softer and deeper, often compared to rainfall or rushing water.
• Brown noise — Even more weighted toward low frequencies; deeper, rumbling sound similar to thunder.

Pink noise has recently drawn attention due to findings suggesting it may reduce REM sleep in certain lab settings. White and brown noise are widely used for sound masking, but high-quality evidence comparing long-term effects on sleep architecture remains limited.

Q: Are there alternatives to sound machines that are safer?
A: Yes. Depending on the source of nighttime noise, alternatives may better preserve sleep quality:

• Earplugs — In laboratory studies, earplugs protected deep sleep more effectively than pink noise during aircraft noise exposure.
• Physical soundproofing — Door sweeps, draft stoppers, heavy curtains and rugs can reduce environmental noise without continuous auditory stimulation.
• Fans or air purifiers at a distance — Provide gentle masking without placing a speaker near your head.
• Behavioral sleep strategies — Consistent bedtime, light control and stress reduction may reduce the perceived need for artificial noise.

If you wake feeling groggy despite adequate sleep duration, consider a one-week trial without broadband noise to assess how your body responds.

A New Series of Health Insights Is on the Way

IMPORTANT

A New Series of Health Insights Is on the Way

Our team has been working behind the scenes to prepare new research and practical health
strategies for our readers. While we finish preparing what’s coming next, we invite you to
explore one of the most-read articles from our library below. See exactly what’s changing →

Alzheimer’s disease doesn’t begin with memory loss — it begins years earlier with a slow, silent shift in your body’s stress chemistry. Long before neurons die, your brain’s hormonal balance starts to erode under constant pressure from everyday stress. The same hormones that once kept you alert and focused start working against you, wearing down your brain’s repair systems and disrupting the flow of energy your cells depend on.

Cortisol, the body’s main stress hormone, plays a central role in this process. When it stays high for too long, it drains your metabolic reserves and interferes with memory formation. Meanwhile, a second hormone called DHEA-S acts as cortisol’s natural counterbalance, helping protect neurons and stabilize brain function.

When the ratio between these two hormones tilts toward cortisol, your brain loses its resilience and becomes more vulnerable to aging and degeneration. This hormonal tug-of-war — shaped by stress, diet, and metabolism — has drawn new attention from researchers exploring why some people develop Alzheimer’s while others do not. The latest findings suggest that long-term hormonal imbalance, not just genetics or plaque buildup, could be one of the earliest warning signs of decline.

Understanding this relationship changes how you think about prevention. By strengthening your metabolism, restoring hormonal balance, and reducing chronic stress, you can support your brain’s ability to heal and adapt — long before symptoms appear. The new research provides a roadmap for how to start.

Stress Hormones Tip the Balance Toward Alzheimer’s

A clinical study published in Cureus examined 85 adults in Serbia — 45 with diagnosed Alzheimer’s disease and 40 healthy peers of similar age and sex — to determine how two hormones, cortisol and DHEA-S, relate to brain health.1 Cortisol is your body’s main stress hormone, while DHEA-S (dehydroepiandrosterone sulfate) acts as its built-in counterbalance — a neurosteroid that supports brain resilience and energy metabolism.

Unlike DHEA, which is the fast-acting, active form, DHEA-S is its sulfated storage form that circulates in your blood far longer and provides a more stable picture of long-term stress balance. By focusing on DHEA-S, the researchers could better gauge chronic stress effects on the brain rather than short-term fluctuations. The scientists wanted to know whether Alzheimer’s patients showed measurable differences in these hormones or in their ratio, which indicates how well your body manages prolonged stress.

• People with Alzheimer’s had higher cortisol levels but not lower DHEA-S — Those with Alzheimer’s showed cortisol levels averaging nearly 399 nanomoles per liter (nmol/L) — about 20% higher than healthy adults — yet their DHEA-S concentrations stayed roughly the same.

This imbalance means the stress response remains chronically activated without the brain’s natural protection. When cortisol dominates, neurons experience more inflammation and less regeneration. The study also noted that this skewed balance was strongest among participants aged 65 to 75, suggesting that middle-to-late adulthood is when stress hormones begin exerting their most damaging effects.

• The cortisol-to-DHEA-S ratio proved to be the real warning sign — Although each hormone alone tells part of the story, the researchers emphasized that their ratio — how much cortisol outweighs DHEA-S — offers a clearer window into chronic stress and brain decline.

In Alzheimer’s patients, that ratio climbed steeply, implying that the body’s defense system against cortisol’s toxicity was failing. This finding helps explain why some people with normal cortisol readings still experience cognitive decline: it’s the imbalance, not just the level, that matters.

• Men and women responded differently, revealing hormonal sensitivity — In healthy adults, men had significantly higher DHEA-S levels than women, meaning their brains could have greater protection from chronic stress. But that sex difference disappeared in those with Alzheimer’s.

The disease seemed to override normal hormonal patterns, flattening DHEA-S levels in both sexes. This means that once neurodegeneration begins, your brain’s ability to maintain hormonal balance — one of its self-defense tools — breaks down.

• Age changed the picture again, suggesting a nonlinear hormonal response — When researchers divided participants by age, they noticed that younger Alzheimer’s patients (60 to 65) had higher DHEA-S levels, which dropped sharply in the 66 to 75 group before rising again after age 75.

This unexpected curve points to a possible window of hormonal collapse, where midlife stress overwhelms the body’s compensatory systems. If you’re in this age range and facing chronic stress, that’s when intervention — stress reduction, adequate rest, and metabolic support — could be most protective for your brain.

Cortisol Acts Like an Overzealous Cleanup Crew That Damages What It’s Meant to Protect

Elevated cortisol increases inflammation and oxidative stress — chemical reactions that corrode neurons and disrupt communication between brain cells. It also suppresses the growth of new neurons in your hippocampus, the brain’s memory center, making it harder to store new information.

In contrast, DHEA-S supports neuronal survival, enhances energy metabolism, and shields brain tissue from the harmful effects of excessive cortisol. When cortisol wins this hormonal tug-of-war, brain networks lose their flexibility and begin to deteriorate.

• Why stress and memory loss are so tightly linked — Chronic cortisol elevation interferes with glucose uptake in brain cells, depriving them of the fuel needed to form memories. It also increases amyloid-beta and tau accumulation — the same proteins that define Alzheimer’s pathology.

Meanwhile, DHEA-S helps counter these effects by enhancing insulin sensitivity and calming overactive immune responses in your brain. In simple terms, one hormone burns your mental circuits, the other repairs them.

• A new biological marker for early intervention — Instead of waiting for memory loss or imaging changes, tracking your cortisol-to-DHEA-S ratio could signal early stress damage years before cognitive symptoms arise.

If your cortisol stays high while DHEA-S falls or stagnates, that’s a red flag. Supporting your metabolic health, prioritizing quality sleep, and restoring hormonal balance could help keep your brain’s internal environment stable long before Alzheimer’s develops.

Lowering Cortisol and Raising Metabolic Energy Could Reverse Brain Decline

In a commentary, bioenergetic researcher Georgi Dinkov analyzed the Cureus study showing that people with Alzheimer’s disease had significantly higher cortisol levels and a skewed cortisol-to-DHEA-S ratio compared to healthy adults.2 He explained that these results validate decades of bioenergetic research linking chronic stress, low metabolism, and neurodegeneration.

Dinkov emphasized that it’s not just elevated cortisol that drives decline — it’s the imbalance between cortisol and protective steroids such as DHEA, testosterone, and progesterone. When this ratio tips toward cortisol dominance, your body remains in a chronic “fight-or-flight” state that accelerates tissue breakdown and cognitive loss.

• Dinkov connected the findings to thyroid-driven metabolic stress — Building on the Cureus data, Dinkov explained that hypothyroidism — a sluggish thyroid that slows metabolic energy production — creates the same hormonal pattern seen in Alzheimer’s patients: high cortisol and suppressed DHEA-S.

When your metabolism slows, your body compensates by ramping up stress hormones to stay alert and energized. But this backfires over time, leading to chronic brain inflammation, poor glucose uptake, and reduced adenosine triphosphate (ATP) production — the energy currency your brain depends on.

• Your cortisol-to-DHEA-S ratio predicts long-term health better than any single hormone — According to Dinkov, this ratio — spotlighted by the Cureus research — is among the strongest predictors of all-cause mortality and neurodegenerative risk. Even when cortisol fluctuates throughout the day, the ratio reveals whether your stress and repair systems are balanced.

Dinkov suggested measuring cortisol and DHEA-S in hair or nails rather than blood, since these tissues reflect long-term hormonal patterns. For anyone trying to gauge chronic stress or cognitive risk, this offers a simple, objective biomarker that’s far more reliable than a one-time blood test.

• Natural compounds help restore hormonal balance and metabolic strength — Dinkov referenced several well-known substances — aspirin, niacinamide (vitamin B3), progesterone, pregnenolone, thyroid support, glycine, and emodin — that help correct the same imbalance observed in the Cureus study. These compounds work by lowering excess cortisol, improving mitochondrial energy output, and supporting the production of protective hormones.

Niacinamide, for instance, increases NAD+, which fuels cellular repair, while aspirin dampens inflammation and cortisol overproduction. Used together, these tools shift your body back into a “rest-and-repair” mode rather than the constant stress chemistry that drives brain aging.

• DHEA acts as a built-in cortisol regulator — Dinkov explained one of the key ways DHEA helps keep cortisol in check: it blocks the enzyme that turns inactive cortisol back “on” and boosts the one that clears excess cortisol from your body. This dual action makes DHEA a natural cortisol buffer that prevents the overactivation of stress pathways.

In other words, DHEA gives your brain a biochemical “cooling system,” stopping cortisol from overheating your neurons. Supporting DHEA through thyroid health, nutrition, and targeted supplementation helps restore this essential balance.

• Stress is a symptom of low energy, not just emotional strain — Dinkov described how the elevated cortisol levels observed in the Cureus Alzheimer’s cohort represent a deeper issue: energy failure. When your cells don’t make enough ATP — whether from poor thyroid output, nutrient deficiencies, or aging — they turn to cortisol to compensate.

The hormone breaks down tissue to release fuel, but that process worsens energy depletion over time. This self-reinforcing loop explains why chronic stress feels endless: it’s a metabolic, not psychological, trap. Dinkov concluded that maintaining a low cortisol-to-DHEA-S ratio protects more than memory — it sustains whole-body resilience.

People who keep this ratio balanced experience better sleep, stable mood, and slower biological aging. His message is practical: by restoring thyroid function, eating enough to prevent energy deficits, and lowering chronic inflammation, you directly influence the biochemical environment that determines whether your brain decays or endures.

Rebuild Your Energy System to Lower Cortisol and Protect Your Brain

If you wake up tired, crash midafternoon, or feel wired when you should be asleep, your body’s stress chemistry has taken over. The Cureus study3 and Dinkov’s review4 both point to the same conclusion: your brain suffers when your cells can’t make enough energy.

To fix that, you have to restore steady fuel, retrain your stress response, and help your body recognize that it’s no longer in survival mode. Here’s how to bring your hormones — and your energy — back into balance:

1. Feed your metabolism the fuel it’s been missing — Cutting carbs keeps your body trapped in a constant stress loop because cortisol spikes whenever blood sugar drops too low. Break that pattern by eating enough healthy carbohydrates — around 250 grams daily — to give your mitochondria a steady energy supply.

Start with gentle foods like fruit and white rice. When your digestion feels stable (no bloating or irregularity), add cooked root vegetables, then more vegetables, legumes, and well-tolerated whole grains. Once your body trusts it’s being fed regularly, cortisol naturally declines, and your energy and focus stabilize.

2. Move in ways that restore instead of deplete — Overdoing endurance exercise or high-intensity intervals keeps your body in fight-or-flight mode long after the workout ends. Cortisol stays elevated, recovery slows, and sleep suffers.

Replace long, punishing sessions with physical activities that build energy rather than drain it — strength training, walking outdoors, dancing, or swimming at an easy pace. Use how you feel afterward as your guide: if you finish feeling grounded and calm, you’ve helped your hormones, not hurt them.

3. Train your nervous system to shift out of stress — Your breath is the fastest lever you have to quiet cortisol and activate your parasympathetic, or “rest and digest,” system. Try rhythmic breathing patterns like 4-7-8 or 4-8 breathing — inhaling for four seconds, holding briefly, and exhaling slowly for seven to eight seconds.

The extended exhale stimulates your vagus nerve, lowering heart rate and cortisol while signaling safety to every organ. Practice before bed, after meals, or whenever tension rises. Over time, your body learns that it no longer needs to live in emergency mode.

4. Rebuild your circadian rhythm through light and sleep — Cortisol follows your light exposure, not your alarm clock. Get outside within an hour of waking to anchor your body’s circadian rhythm, and dim screens and overhead lighting at night so melatonin can rise naturally.

Keep your bedtime and wake-up times consistent — even on weekends — to lock in hormonal balance. Deep, regular sleep clears stress hormones, strengthens memory, and repairs brain tissue. If you’re dragging through the day, fix your light and sleep first instead of relying on caffeine.

5. Use natural progesterone to quiet the cortisol surge — Bioidentical progesterone acts as your body’s built-in cortisol brake, restoring calm where chronic stress has hijacked balance. Unlike synthetic versions, natural progesterone fits perfectly into your body’s own receptor system, lowering cortisol’s overstimulation and supporting deep rest.

FAQs About Cortisol and Alzheimer’s Disease

Q: What did the new Alzheimer’s study reveal about cortisol and DHEA-S?
A: Researchers found that people with Alzheimer’s disease had cortisol levels roughly 20% higher than healthy adults, while their DHEA-S levels stayed about the same. This created a skewed cortisol-to-DHEA-S ratio — meaning stress hormones were overpowering the brain’s natural defenses. That imbalance, not just genetics or amyloid buildup, appears to drive the early stages of brain decline.

Q: How are DHEA and DHEA-S different?
A: DHEA is the fast-acting form of the hormone, while DHEA-S is the stable, long-lasting form stored in your blood. Because DHEA-S changes slowly, it’s a better measure of long-term stress and brain resilience. It also acts as a neurosteroid, helping neurons resist inflammation and oxidative damage while buffering cortisol’s harmful effects.

Q: What did Georgi Dinkov’s analysis add to this research?
A: Dinkov explained that the Cureus study confirms a broader principle: high cortisol and low metabolic energy often go hand in hand. He connected these hormone shifts to thyroid sluggishness, nutrient depletion, and aging — all of which drain cellular energy and raise stress chemistry. He also noted that maintaining a low cortisol-to-DHEA-S ratio predicts not just better memory but longer life and greater overall resilience.

Q: What practical steps help lower cortisol and restore hormonal balance?
A: To calm your stress system, start by fueling your metabolism. Eat enough healthy carbohydrates — about 250 grams per day — to keep blood sugar stable. Cut back on overtraining, use rhythmic breathing to activate your vagus nerve, and rebuild your circadian rhythm by getting morning sunlight and sleeping on a consistent schedule. These changes lower cortisol naturally while improving energy and mental clarity.

Q: How does progesterone fit into this picture?
A: Natural progesterone acts as a built-in cortisol blocker. Your body recognizes it as a calming, balancing hormone that reduces overstimulation, helps you sleep deeply, and stabilizes mood. Natural progesterone effectively blocks cortisol by reducing blood concentrations, helping restore hormonal harmony, protecting your brain and body from the long-term effects of stress.