Sleep

Sleep is the highest-ROI lever in longevity behavior. Cohort data consistently show that short sleep (<6 h), long sleep (>9 h), poor sleep regularity, and untreated sleep apnea each independently predict all-cause mortality, cardiovascular disease, dementia, metabolic disease, and depression.

Despite its centrality, sleep is also one of the most-meddled-with-and-misunderstood health behaviors. The 8-hour rule is approximately right; sleep regularity matters as much as duration; and most over-the-counter "sleep aids" are weak or harmful at scale.

What the evidence actually supports

Strong:

• 7–8 hours of sleep on a regular schedule is associated with the lowest cardiovascular and all-cause mortality risk. The dose-response is U-shaped — both short and long sleep carry risk.
• Sleep regularity (going to bed and waking up at consistent times) independently predicts mortality at least as strongly as duration. The 2023 Windred et al. Sleep study found regularity outperformed duration as a mortality predictor. See Circadian rhythms for why timing turns out to matter as much as duration.
• CBT-I (cognitive behavioral therapy for insomnia) is the first-line treatment for chronic insomnia. It outperforms drugs in head-to-head trials and effects persist after treatment ends. See Treating chronic insomnia for the case against chronic Z-drugs and benzos.
• Untreated obstructive sleep apnea (OSA) raises mortality, hypertension, atrial fibrillation, stroke, and dementia risk substantially. CPAP ≥4 h/night in moderate-severe OSA reduces cardiovascular events. OSA is dramatically underdiagnosed in midlife — see Sleep-disordered breathing.

Moderate:

• Light exposure: bright morning light + dim/warm evening light strengthens circadian alignment and improves both sleep and mood.
• Cool bedroom (18–20°C / 65–68°F) supports the natural core-temperature drop that initiates sleep.
• Magnesium (200–400 mg, glycinate form) has small but real effects on subjective sleep, especially in those with low intake. See Sleep supplements for the rest of the supplement landscape — melatonin, L-theanine, ashwagandha, glycine, valerian, CBD — and which (if any) are worth using long-term.
• A 20-minute power nap is one of the most efficient cognitive boosters in physiology. A daily 90-minute nap in midlife is a different signal entirely — an independent warning for cardiovascular disease, dementia, and earlier death. See Daytime naps for the duration, timing, and activity-level boundaries.

Weak / preliminary:

• L-theanine, ashwagandha, glycine, and melatonin all have modest, narrow indications. None are first-line for chronic insomnia.

Caution:

• Chronic use of benzodiazepines, Z-drugs, and OTC antihistamines (Benadryl, ZzzQuil) — particularly over age 50 — increases falls, fractures, cognitive impairment, and dementia risk.
• Alcohol as a sleep aid fragments sleep architecture (suppresses REM, increases wakefulness in second half of night).

Practical sleep checklist (evidence-weighted)

1. Anchor your wake time first. Same time every day, weekends included. The CNS adapts to consistent waking; it does not adapt to consistent sleep onset.
2. Get morning light (10–30 min outdoors within 1 hour of waking). The strongest zeitgeber.
3. Dim the evening. Reduce overhead lighting and screens 1–2 hours before bed.
4. Cool bedroom, dark room. 18–20°C / 65–68°F; blackout curtains; remove glowing electronics.
5. No caffeine after ~10–12 hours pre-bed (caffeine half-life is 5–6 h; varies by genotype).
6. No alcohol within 3 hours of bed. It hastens onset but fragments architecture.
7. Screen for OSA if you snore loudly, gasp/choke at night, have hypertension, atrial fibrillation, or BMI ≥30. Use the STOP-Bang questionnaire as a starting point.^[1]
8. For chronic insomnia, start with CBT-I, not pills. Digital programs (e.g., Sleepio, Somryst) have RCT support and are accessible.
9. Don't mouth-tape without a clinical evaluation. Address nasal obstruction first if needed.

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