# Sleep — A Third of Life, Finally Examined Canonical URL: https://shipslides.com/d/catalog-health-sleep Raw viewer URL: https://content.shipslides.com/d/catalog-health-sleep/raw Category: Health Slides: 13 Updated: 2026-05-17T20:55:55.691Z Tags: catalog, health, sleep ## Summary a third of life, finally examined Key sections include: SLEEP /; Sleep is universal; Two forces, one night: C + S; Stages of the night; What sleep does; How much do you need?; Architecture: deep vs. dreaming; The dream; Modern dysfunction; Insomnia & CBT-I. ## Slide Outline 1. SLEEP / 2. Sleep is universal 3. Two forces, one night: C + S 4. Stages of the night 5. What sleep does 6. How much do you need? 7. Architecture: deep vs. dreaming 8. The dream 9. Modern dysfunction 10. Insomnia & CBT-I 11. Sleep apnea 12. Practical advice 13. Further reading ## Slide Transcript ### Slide 1: SLEEP / - a third of life, finally examined ### Slide 2: Sleep is universal - Every animal we have looked closely at sleeps — or does something so close to it that the difference is academic. - Fruit flies, jellyfish, octopuses, fish, mice, elephants, humans. - Dolphins and some birds sleep one hemisphere at a time, keeping one eye open. - Sleep is so costly — predator-vulnerable, opportunity-blind — yet evolution has kept it for hundreds of millions of years. - That alone tells us: whatever sleep does, it cannot be done any other way. ### Slide 3: Two forces, one night: C + S - Process C — Circadian - An internal ~24-hour clock anchored in the suprachiasmatic nucleus. Light (especially morning sun) sets it. It says when you should sleep. - Process S — Sleep Pressure - Adenosine builds up in the brain the longer you are awake. It says how badly you need sleep. Caffeine works by blocking it. - The two waves intersect: maximum sleepiness when both are aligned at night, brief afternoon dip ("siesta hour") when S is high but C lifts. ### Slide 4: Stages of the night - A healthy adult cycles through sleep stages roughly every 90 minutes, four to six times a night. - Deep slow-wave sleep dominates the first half of the night. REM grows longer in the second half — which is why oversleeping in the morning feels dream-heavy. ### Slide 5: What sleep does - Memory - consolidation - Glymphatic - brain washing - Immune - repair & defense - Emotion - regulation - Hippocampus → cortex transfer: the day's experiences are replayed and filed away during slow-wave sleep. - Glymphatic flushing: cerebrospinal fluid clears metabolic waste — including beta-amyloid linked to Alzheimer's. - Cytokines & T-cells rise during sleep; one bad night meaningfully blunts vaccine response. - Amygdala recalibration: REM dampens emotional charge of memories — "the night soothes." ### Slide 6: How much do you need? - 7–9 hmost adults - 9–11 hschool-age children - 14–17 hnewborns - < 1%true short sleepers - Chronically running on under 6 hours is associated with measurably higher risks of cardiovascular disease, type-2 diabetes, depression, certain cancers, and early mortality. You cannot adapt — you adapt to feeling worse. ### Slide 7: Architecture: deep vs. dreaming - Slow-wave (N3): hippocampus broadcasts the day's facts to the cortex. Sharp-wave ripples orchestrate the transfer. - REM: brain is as active as waking, body paralyzed (atonia). Skill consolidation, creative recombination, emotional defanging. - Lose deep sleep → lose declarative memory. Lose REM → lose emotional balance and procedural skill. ### Slide 8: The dream - Most vivid in REM sleep, when the brain is paradoxically as active as waking but cut off from sensory input and motor output. - Memory rehearsal - Dreams replay and remix the day's experiences, weaving new information into existing networks. - Threat simulation - An evolutionary rehearsal space: practice predators, social danger, falls — without the cost of dying. - Emotional regulation - Noradrenaline drops to zero in REM — the brain processes painful memories without their sting. - Random noise? - Hobson's "activation-synthesis": dreams are the cortex inventing stories from random brainstem signals. ### Slide 9: Modern dysfunction - Industrial life has assembled an almost perfect attack on sleep: - Blue light from screens after dusk suppresses melatonin and pushes the circadian clock later. - Shift work chronically misaligns Process C; classified by the WHO as a probable carcinogen. - Caffeine's half-life is ~6 hours — a 4pm coffee leaves a quarter still working at midnight. - Anxiety & rumination activate the sympathetic nervous system, the opposite of what sleep needs. - Alcohol sedates but fragments the night — REM is suppressed, sleep is shallower. - Average sleep has fallen from ~8.5h (1942) to ~6.8h today. ### Slide 10: Insomnia & CBT-I - For chronic insomnia, cognitive-behavioral therapy for insomnia (CBT-I) is the first-line treatment recommended by sleep medicine bodies — more effective than sleeping pills long-term. - Stimulus control: bed is for sleep only. If you can't sleep in 20 min, get up. - Sleep restriction: compress time in bed to rebuild sleep efficiency, then gradually expand. - Cognitive restructuring: dismantle catastrophic beliefs ("I'll fail tomorrow") that drive arousal. - Relaxation training + consistent wake time, every day. - Hypnotics (Ambien, etc.) produce sedation, not natural sleep — and tolerance, dependence, and rebound insomnia are common. ### Slide 11: Sleep apnea - Roughly ~30% of adults have some degree of obstructive sleep apnea. The majority of moderate-to-severe cases are undiagnosed. - The airway collapses repeatedly; the brain micro-arouses to gasp, hundreds of times a night. - Sleep architecture is shredded — minimal deep sleep, minimal REM. - Consequences: hypertension, atrial fibrillation, stroke, heart failure, cognitive decline, daytime fatigue. - Snoring loudly + waking unrefreshed + observed pauses → ask for a sleep study. - CPAP remains the gold-standard treatment; new therapies (mandibular devices, hypoglossal nerve stimulation) are expanding options. ### Slide 12: Practical advice - Cool~65°F / 18°C - Darkblackout if needed - Quietor steady noise - Regularsame wake time daily - Morning sunlight within an hour of waking — anchors Process C. - No caffeine after roughly noon; honestly, earlier if you're sensitive. - Last meal 2–3 hours before bed; alcohol is not a sleep aid. - Wind-down ritual: dim lights, screens off or in night mode 60 min before bed. - If you can't sleep, leave the bed and read in dim light until drowsy. - Protect the same wake time on weekends — "social jetlag" is real. ### Slide 13: Further reading - Sleep science is one of the youngest mature fields in biology. A few starting points: - Matt Walker — "Why We Sleep" lectures (YouTube) - Sleep stages & REM explained (YouTube) - "Sleep is the single most effective thing we can do to reset our brain and body health each day." — Matthew Walker ## Related Decks - [The Science of Sleep](https://shipslides.com/d/health-sleep-science) - [Aging — The Mechanics of Getting Older](https://shipslides.com/d/catalog-health-aging) - [Anatomia humana — a guided tour](https://shipslides.com/d/catalog-health-anatomy) - [Medical Breakthroughs — The Big Steps That Saved Lives](https://shipslides.com/d/catalog-health-breakthroughs)