Kat Fu, M.S., M.S.

Can one night of sleep flag dementia risk?

How you sleep is tied to memory, mood, blood pressure, blood sugar, and whether you can show up for the people and activities that matter to you. For years, though, the tools we’ve had to measure sleep and long-term health risk have been fairly blunt: “how many hours,” questionnaires, or a diagnosis like sleep apnea.

Now something new is arriving: large AI models that look at every second of your sleep study and try to map that pattern to future health. One of the latest examples is the 2026 project, SleepFM—developed by a multi-institution collaboration including researchers at Stanford & Harvard.

SleepFM is a “foundation model” trained on more than half a million hours of clinical polysomnography (full overnight sleep studies with EEG, breathing, heart rhythm, and more).

From one overnight sleep study, it can estimate risk for conditions ranging from dementia to heart failure and all-cause mortality.

At the same time, other human studies are sharpening the picture of which features of sleep matter most in later life: how much deep slow-wave sleep you get, how stable your emotional brain feels after sleep, and how “old” or “young” your brain looks.

In this article, we’ll cover:

How the 2026 SleepFM study uses one overnight sleep study to predict risk for about 130 conditions, including dementia and cardiovascular disease.

What new work in older adults shows about deep non-REM slow-wave sleep and anxiety, and why that matters for brain aging..

How slow-wave sleep loss over years relates to your chance of developing dementia in late life.

How deep-learning models that estimate your “sleep age” from overnight studies connect to life expectancy.

All of this will stay grounded in what you can actually do with this knowledge: how to think about getting a sleep study, how to protect the parts of sleep that seem most tightly linked to brain and heart health, and how to view these new AI tools in a measured helpful way.

Let’s get started.

Can one night of sleep flag dementia risk? Read Post »

Hormonal Sleep Disruption in Women: What It Is, How It Fragments Sleep, and How to Recognize It

Overview: Estrogen, progesterone, and their downstream metabolites regulate multiple pathways that govern sleep — from the brain’s inhibitory tone to body temperature to the neurotransmitters that set the sleep-wake cycle. As these hormones’ function is disrupted during perimenopause and menopause, each pathway is affected in a specific way: Progesterone is converted to allopregnanolone, a neurosteroid

Hormonal Sleep Disruption in Women: What It Is, How It Fragments Sleep, and How to Recognize It Read Post »

Hormonal Sleep Disruption in Men: How Declining Testosterone Function, Growth Hormone, and DHEA Fragment Sleep After 40

Testosterone, growth hormone, and DHEA all decline as men age — starting as early as the late 20s and accelerating after 40. These hormonal changes don’t reduce sex drive and muscle mass alone; they directly alter the brain’s ability to produce and maintain deep sleep. Declining testosterone function involves three concurrent changes: falling production from

Hormonal Sleep Disruption in Men: How Declining Testosterone Function, Growth Hormone, and DHEA Fragment Sleep After 40 Read Post »

Metabolic Sleep Disruption: How Metabolic Impairment Fragments Sleep and How to Recognize It

Overview: Metabolic impairment — including insulin resistance, blood sugar instability, mitochondrial decline, and disrupted fat metabolism — can directly fragment sleep and degrade its deepest and restorative stages. Five mechanisms contribute: Insulin resistance suppresses slow-wave sleep — the deepest sleep stage responsible for overnight metabolic restoration — creating a self-reinforcing cycle where less deep sleep

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Circadian Rhythm Disruption: How a Misaligned Internal Clock Fragments Sleep, Drives 3AM Wakeups, and Reduces Sleep Depth

Overview: Circadian disruption occurs when the body’s internal ~24-hour clock — controlled by the suprachiasmatic nucleus in the hypothalamus — loses alignment with the external light-dark cycle or with the body’s own organs and tissues. Five mechanisms link circadian disruption to fragmented sleep, 3am wakeups, and light shallow sleep: Orexin timing misalignment — the suprachiasmatic

Circadian Rhythm Disruption: How a Misaligned Internal Clock Fragments Sleep, Drives 3AM Wakeups, and Reduces Sleep Depth Read Post »

Inflammatory Sleep Disruption: How Chronic Inflammation Fragments Sleep and How to Recognize It

Overview: Inflammatory sleep disruption occurs when persistent, low-level immune activation — elevated cytokines, overactive inflammatory pathways, and immune cells in a sustained activated state — can interfere with the biological processes that produce and maintain sleep. Five mechanisms appear to contribute to it: Cytokine overload — chronic elevation of IL-6, TNF-α, and IL-1β is associated

Inflammatory Sleep Disruption: How Chronic Inflammation Fragments Sleep and How to Recognize It Read Post »

More Magnesium Won’t Help You Sleep

Magnesium supplementation addresses one contributor to sleep disruption—low magnesium—and its benefit tops out once deficiency is corrected. When sleep maintenance problems persist after supplementation, the remaining causes tend to be circadian, hormonal, inflammatory, or metabolic, and each requires a different approach than compounds built for neural downregulation. – Serum magnesium reflects roughly 1% of total

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You Don’t Feel the Acid Reflux Waking You

Acid can rise into the esophagus during sleep and fragment your rest without any heartburn. During sleep, swallowing frequency drops, saliva production decreases, peristalsis becomes less active, and lying flat removes gravity — meaning acid that would be neutralized in seconds while upright can sit against the esophageal lining for minutes, triggering a protective arousal

You Don’t Feel the Acid Reflux Waking You Read Post »

Autonomic Sleep Disruption: What It Is, How It Fragments Sleep, and How to Recognize It

Overview: Autonomic sleep disruption occurs when the body’s involuntary regulation — heart rate, stress hormones, and neural inhibition — fails to transition properly into sleep mode. Three mechanisms can drive it: Weakened vagal tone — parasympathetic activation doesn’t engage at sleep onset, leaving heart rate elevated through the night Reduced GABA — the brain’s primary

Autonomic Sleep Disruption: What It Is, How It Fragments Sleep, and How to Recognize It Read Post »

Is your gut spiking cortisol at 3 a.m?

Sleep and the gut.

Two areas of longevity science I keep coming back to — both in my own work and in my own health. I think the gut-sleep connection is one of the more underappreciated intersections in health, and it’s something I’ve wanted to explore in a focused conversation for a while.

Today I get to do that — through a written Q&A with Scott C. Anderson.

Scott is a science journalist and co-author of The Psychobiotic Revolution: Mood, Food, and the New Science of the Gut-Brain Connection — a National Geographic bestseller he wrote alongside John F. Cryan and Ted Dinan, the researchers who coined the term psychobiotics. He also writes on Substack about the gut-brain connection.

I asked Scott six questions about the gut-brain axis, cortisol, probiotics, and what the research says about improving sleep through the microbiome.

Here’s what he had to say:

Is your gut spiking cortisol at 3 a.m? Read Post »

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