Metabolic Sleep | The Longevity Vault

Does Visceral Fat Block Your Growth Hormone Pulses During Sleep?

Yes. Visceral fat independently suppresses pulsatile growth hormone secretion during sleep. In premenopausal women, those with high visceral fat showed a 4-fold reduction in mean plasma growth hormone compared to lean controls — driven by jointly diminished basal and pulsatile secretion. Visceral adiposity alone explained 22% of the variability in GHRH-driven growth hormone output, after […]

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Does Keto Cause 3am Waking? What Happens to Blood Sugar When You Cut Carbs

Carbohydrate restriction depletes liver glycogen — the stored glucose the brain draws on during sleep. When the normal 3-4am cortisol rise occurs, the liver has less glycogen to release and relies more on gluconeogenesis, where cortisol stimulates glucose production from non-carbohydrate sources like amino acids and glycerol. In a 2026 study of 220 people with

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Why Does Intermittent Fasting Disrupt Your Sleep?

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

When a fasting window extends past 12-14 hours, the liver runs low on stored glycogen. To keep the brain fueled overnight, the body turns to gluconeogenesis — manufacturing glucose from amino acids and lactate — a process accompanied by rises in cortisol and growth hormone. These hormones activate the brain’s arousal centers, and can produce

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Can a Continuous Glucose Monitor Show Why You Wake Up at 3am?

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

Yes. A continuous glucose monitor records blood sugar every few minutes overnight, capturing drops and spikes that fingerstick testing misses. Research shows that standard fixed-overnight analysis windows miss a median 57 minutes of measured sleep and hypoglycemic episodes (Trawley et al., 2024). CGM data can reveal whether a nocturnal glucose dip is triggering the stress

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Can Prediabetes Cause Sleep Problems?

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

Yes. Prediabetes is associated with changes in sleep architecture — including a reduction of approximately 6 minutes of REM sleep per night and a higher likelihood of fragmented, unrefreshing sleep. 62% of adults with prediabetic glucose levels report poor sleep, compared to 46% with normal glucose. The relationship runs in both directions: short or disrupted

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Does Insulin Resistance Affect Sleep Quality?

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

Yes. Insulin resistance suppresses slow-wave sleep — the deepest and primary restorative stage — without necessarily reducing total sleep time. A 2008 crossover study found that selectively suppressing slow-wave sleep for three nights reduced insulin sensitivity by approximately 25% in healthy adults, with a correlation of r = 0.89 between slow-wave sleep loss and insulin

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Is Waking Up at 3am a Sign of Adrenal Fatigue?

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

“Adrenal fatigue” is not a recognized endocrine condition, but the 3am waking pattern it describes is documented and measurable. The research identifies two distinct HPA axis states that produce different sleep disruption patterns: hyperactivation (elevated nocturnal cortisol, associated with accumulated stress) and hypoactivation (blunted cortisol response, associated with prolonged psychological burden). These are opposite ends

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Can a Calorie Deficit Cause Insomnia?

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

Yes. Caloric restriction elevates cortisol — the body’s primary stress hormone — which delays the overnight cortisol nadir, increases the number of nocturnal awakenings, and fragments sleep architecture. The effect is dose-dependent: moderate restriction does not reliably raise cortisol, while fasting-level deficits produce larger and more consistent elevations. Sleep extension may offset some of the

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Why Does Cortisol Spike at 3am and Wake You Up?

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

Cortisol rises during the second half of the night as part of the circadian rhythm, preparing the body for waking. When that rise comes too early, too steeply, or from a dysregulated baseline, it activates the brain’s arousal circuits and produces a 3am waking — often with racing thoughts, a sense of unease, or a

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Why Do You Wake Up Hungry at 3am?

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

Waking up hungry at 3am is driven by two overlapping mechanisms: a blood sugar drop that triggers stress hormones and hunger, and a disruption in the hormones that regulate appetite — leptin (which suppresses hunger) and ghrelin (which drives it). Sleep restriction suppresses leptin and elevates ghrelin, creating a hormonal environment where hunger fires during

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