MODULE 05 · 45 min

Sleep, Stress & Circadian Health

The most underrated longevity lever — and the easiest to wreck.

In progress

Quiz 0/3

Core summary

Sleep is when your brain takes out the trash and your body repairs itself. Most adults need 7–9 hours; chronically getting much less is linked to dementia, heart disease, and shorter life. The big levers: keep a regular schedule, get morning light, dim lights at night, keep the room cool, and watch alcohol.

Topics covered

01Sleep architecture and age-related changes
02Glymphatic clearance and Alzheimer's risk
03Sleep duration U-curve and mortality
04Circadian disruption, shift work, light hygiene
05Allostatic load and chronic stress
06Mind-body practices: meditation, breathwork, HRV biofeedback

Learning objectives

→Explain the U-shaped curve between sleep duration and mortality.
→Describe glymphatic clearance and its relevance to neurodegeneration.
→Identify high-impact sleep hygiene levers (light, temperature, alcohol, timing).
→Distinguish evidence-based stress interventions from wellness theater.

Key takeaways

→Both <6 and >9 hours of sleep correlate with higher mortality — but causality runs both ways.
→Alcohol fragments sleep architecture more than people realize.
→Chronic stress acts through HPA, sympathetic, and immune pathways — interventions must target the mechanism.

Graded claims

Chronic short sleep (<6h) increases all-cause mortality risk

Supported, context-specific — Confounded by reverse causation but consistent.

Untreated OSA increases CV mortality

Clinically established — Strong observational and mechanistic data.

CBT-I outperforms sleeping pills for chronic insomnia

Clinically established — First-line per AASM guidelines.

Mouth taping cures sleep apnea

Misleading or false — No evidence; can be harmful in OSA.

Blue-blocking glasses meaningfully improve sleep

Plausible, unproven in humans — Modest signal; ambient light reduction matters more.

Quick check

1. Glymphatic clearance is most active during:

2. First-line treatment for chronic insomnia per major guidelines?

3. Sleep duration and mortality form a: