Blog | The Longevity Vault

Why Are You Wired but Tired, and What Role Do Mitochondria Play?

The wired-but-tired state is a measurable physiological condition. A meta-analysis of 20 studies found that people with chronic insomnia have elevated cortisol (SMD = 0.50), consistent with 24-hour hypothalamic-pituitary-adrenal axis hyperactivation (Dressle et al., 2022). Mitochondria sit at the center of this pattern: a PNAS study in mice demonstrated that mitochondrial function directly tunes adrenal […]

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Why Does NAD+ Drop Faster in Women After 40 — And What Does That Mean for Sleep?

During perimenopause and menopause, women lose NAD+ through two concurrent pathways: the age-related reduction that affects everyone, and an accelerated ovarian-specific depletion driven by rising CD38 and PARP activity in reproductive tissue. All three NAD+ synthesis pathways — kynurenine, Preiss-Handler, and salvage — show coordinated downregulation in aging oocytes (Di Emidio et al., 2024). No

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Does the NLRP3 Inflammasome Disrupt Sleep?

Inflammatory Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

Yes. The NLRP3 inflammasome is an intracellular immune complex that activates during sleep deprivation, releasing the inflammatory cytokines IL-1beta and IL-18 and triggering pyroptosis (inflammatory cell death) in neural tissue. NLRP3 knockout mice show reduced deep sleep rebound after sleep deprivation. In chronic insomnia with short sleep duration, peripheral NLRP3 components are upregulated compared to

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Does Evening Exercise Delay Your Circadian Clock — or Is Disruption Smaller Than You Think?

Circadian Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

It depends on two variables the blanket advice omits: strain intensity and chronotype. The largest study ever conducted on evening exercise and sleep — tracking 14,689 people across 4 million nights — found that high-strain exercise finishing at least four hours before sleep causes no meaningful disruption, while maximal-strain exercise within two hours delays sleep

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How Long Do Probiotics Take to Improve Sleep? What the Research Shows Week by Week

Autonomic Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

Research shows initial sleep quality improvements at 4 weeks, with continued effects at 8 weeks and beyond. A 2024 meta-analysis of 15 trials comparing supplementation durations found that both 4-6 week and 8-16 week supplementation windows showed significant PSQI improvements (Ito et al., 2024). A Bifidobacterium breve trial documented measurable PSQI improvement at 4 weeks

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Is Your Insomnia a Nervous System Problem? How to Tell the Difference

Autonomic Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

Insomnia can be driven by nervous system overactivation. The hyperarousal model — supported by EEG, neuroimaging, and neuroendocrine studies — shows that many people with chronic insomnia have measurable nervous system overactivation: elevated cortisol, higher heart rate at sleep onset, and reduced parasympathetic recovery. A 2023 review found that hyperarousal appears to be a persistent

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Can Your Eye Exam Predict How Long You’ll Live?

Circadian Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

Deep learning models trained on retinal photographs can estimate how old the body is — independent of chronological age — with a mean error of under 3 years. When the predicted retinal age exceeds chronological age, each 1-year gap is associated with a 2% increase in all-cause mortality risk. The retinal age gap reflects vascular,

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Why Does One Glass of Wine Ruin Your Sleep During Menopause?

Sleep & 3AM Wakeups, Women's Hormones and Sleep / Kat Fu, M.S., M.S.

Alcohol disrupts menopause sleep through three pathways: it suppresses REM architecture even at low doses; it triggers vasodilation in a body whose thermoneutral zone is already narrowed by estrogen depletion, raising hot flash frequency; and it alters estrogen metabolism through hepatic enzyme interactions, with the strongest hormonal effects occurring when gonadotropins are elevated — the

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Which Circadian Mechanisms Change After 40 — and Which Ones Are Reversible?

Circadian Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

At least six circadian mechanisms change after 40: the SCN loses amplitude as VIP neurons decline, melatonin production drops from pineal calcification, the cortisol rhythm advances earlier, the core body temperature rhythm flattens, lens yellowing reduces blue light reaching the retina, and peripheral clocks become harder to re-entrain through exercise. Some of these are structural

Which Circadian Mechanisms Change After 40 — and Which Ones Are Reversible? Read Post »

How Does Your Vagus Nerve Actively Suppress Inflammation?

Autonomic Sleep, Sleep & 3AM Wakeups / Kat Fu, M.S., M.S.

The vagus nerve actively suppresses inflammation through a specific molecular circuit called the cholinergic anti-inflammatory reflex. Efferent vagal fibers release acetylcholine that binds to alpha-7 nicotinic acetylcholine receptors on macrophages, directly suppressing TNF-alpha production. A 2003 Nature study proved this receptor is strictly required: knockout mice lacking the alpha-7 subunit received no anti-inflammatory benefit from

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Tests, Fixes, and Ideas That Are Shaping My Longevity Strategy