How many hours should I sleep?

7–9 h for most adults. Individual variation exists — some do well on 6.5 h, others need 9. Test: do you wake refreshed without an alarm? Does daytime alertness hold?

Does weekend catch-up sleep repair weekday debt?

Partially — glucose tolerance and hormones recover, but ~50% of the metabolic damage sticks (Broussard, 2016). A consistent rhythm beats compensation.

Is melatonin safe long term?

Short-term (weeks, e.g. jet lag) — yes. Daily long-term use likely suppresses endogenous production. Low doses (0.3–1 mg) work better than high (5–10 mg).

Why do I wake at 3–4 am?

The most common cause is an early cortisol rise (stress, low blood sugar, evening alcohol). Consider magnesium, alcohol-free dinner, stress work and, if needed, a salivary cortisol day profile.

Academy

Sleep and recovery

Sleep — the foundation of metabolic health

Sleep is not 'wasted time' — it is an active hormonal, immune and metabolic recovery process. Chronic sleep restriction (< 6 h) raises insulin resistance, cortisol, appetite and inflammation as much as a poor diet.

1 week of < 6 h sleep = ~40% worse insulin sensitivity
Deep sleep and REM — the glymphatic system clears the brain
Cortisol, melatonin, growth hormone — in sync with the sun

See webinars Sleep checklist

Why sleep underpins every system

During sleep the body doesn't 'switch off' — the opposite happens: the glymphatic system flushes metabolic waste from the brain (including beta-amyloid), deep-sleep stages restore tissues via growth hormone, and REM consolidates memory and emotional regulation.

Sleep quality matters as much as duration. 8 h of fragmented sleep with low deep-sleep share is worse than 7 h of continuous deep sleep.

Early signs of poor sleep

Waking without an alarm is hard; morning 'fog' lasts > 30 min
Waking at 3–4 am (early cortisol rise)
Falling asleep takes > 30 min or is 'too fast' (< 5 min = sleep debt)
Night sweats, restless legs (RLS)
Snoring, breathing pauses (possible sleep apnea)
Afternoon carb cravings, evening snacking
Reduced stress tolerance, irritability, poor focus

Sleep and insulin sensitivity

In the classic Van Cauter & Spiegel study (Lancet, 1999) healthy men were restricted to 4 h of sleep for 6 nights — glucose tolerance dropped by 40%, into pre-diabetic range. The effect resolved after normal sleep resumed.

Every hour of lost sleep raises next-day average insulin and appetite (leptin ↓, ghrelin ↑) — one reason sleep-deprived people spontaneously eat 300–500 kcal more.

Cortisol cycle and circadian rhythm

Cortisol should peak in the morning (30 min after waking — CAR)
In the evening (after 20:00) cortisol should fall — otherwise insomnia
Evening blue light (screens) suppresses melatonin by 50–90%
Morning natural light (10 min in the first hour) resets the cycle

Deep sleep, REM and hormonal recovery

Deep sleep (N3, delta waves) dominates the first half of the night — this is when growth hormone spikes, tissue repair happens and the glymphatic system clears the brain. REM dominates the second half — memory consolidation and emotional processing.

Alcohol and late meals reduce deep-sleep share. Hard training right before bed (< 2 h) can raise cortisol and delay sleep onset.

Four pillars of better sleep

Before sleeping pills — try these four pillars consistently for 2–4 weeks. In most cases sleep improves substantially.

Light

10–20 min of natural morning light in the first hour. In the evening: screens on f.lux/night-shift, after 21:00 dim lights (< 100 lux), bedroom fully dark.

Temperature and rhythm

Bedroom 17–19 °C. Consistent wake and bedtime ± 30 min (including weekends). Dinner at least 2–3 h before bed.

Caffeine and alcohol

Caffeine half-life is 5–6 h — last cup before 14:00. Alcohol shortens REM and deep sleep — limit and prefer early evenings.

Stress and movement

Daily 30 min of movement (not right before bed). Evening down-regulation — breathwork, journaling, reading on paper. Meditation or NSDR 10 min.

Supplements for sleep (only when needed)

Before supplements — dial in light, caffeine, alcohol, training timing and stress. With the fundamentals in place, supplements work far better.

Magnesium (bisglycinate or threonate, 200–400 mg evening) — relaxing, improves deep sleep
L-theanine (200 mg) — reduces pre-sleep anxiety
Glycine (3 g) — lowers body temperature, speeds sleep onset
Apigenin (chamomile extract, 50 mg) — GABAergic effect
Melatonin (0.3–1 mg) — SHORT-TERM (e.g. jet lag), not long-term
Ashwagandha (300–600 mg) — lowers cortisol if stress is the driver
Avoid: 'strong' 5–10 mg melatonin products — likely suppress endogenous production

Eating window and sleep

Late eating (< 2 h before bed) raises overnight glucose and insulin, reduces deep sleep and the GH pulse. Time-restricted eating (last meal 19:00–20:00) improves sleep quality for most people within weeks.

Very strict fasting (< 500 kcal/day) can worsen sleep in the first weeks — give the body 2–3 weeks to adapt.

Labs that add sleep context

Salivary cortisol day profile (4 samples) — cortisol curve
Fasting glucose and insulin, HOMA-IR — metabolic context
Ferritin, TIBC — iron deficiency drives RLS and fragmented sleep
TSH, free T3 — thyroid affects night temperature and sleep
Vitamin D, magnesium (RBC), zinc — common deficiencies
If snoring + breathing pauses — consider a sleep-apnea study (home polygraphy)

Go deeper: sleep and circadian webinars

Recorded material on sleep science, the cortisol rhythm and practical interventions.

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