sleep whatnot

Fast facts

  • We spend ~1/3 of life asleep.

  • Sleep = active brain state (not unconscious shutdown).

  • Night structure: deep (slow-wave) sleep early; REM later.

Brain waves (know the numbers)

  • Beta 13–30 Hz — awake, active thinking.

  • Alpha 8–12 Hz — awake, resting (relaxed, Netflix).

  • Theta 4–7 Hz — indicator of sleep onset.

  • Delta < 3.5 Hz — deep, slow-wave sleep.
    (Think: higher frequency = short waves; lower frequency = tall slow waves.)

Two main sleep classes

  • NREM (non‑REM): three stages (light → deep).

  • REM: brain looks “awake” on EEG; vivid dreams; muscle paralysis.

NREM quick-reference

  • Stage 1 (light, ~5 min):

    • Mostly alpha → some theta; brief; reduced heart rate/muscle tone; vertex spikes possible.

  • Stage 2 (light):

    • Predominantly theta; sleep spindles (12–14 Hz) and K‑complexes (unique to S2).

    • Spindles = memory consolidation (learning before sleep → more spindles).

    • K‑complexes = cortical downshift; block external noises.

    • Myoclonic jerk = falling sensation sometimes.

  • Stage 3 (slow‑wave / deep):

    • Dominated by delta waves; hard to wake (groggy if woken).

    • Sleepwalking/talking, simple “boring” dreams; early night concentrated.

REM sleep (paradoxical sleep)

  • EEG: low‑amplitude, high‑frequency (looks awake; beta-like).

  • Features: rapid eye movements, near‑complete skeletal muscle paralysis, vivid/illogical dreams (low prefrontal control), active sensory cortex.

  • Mostly occurs in second half of the night; critical for motor skill memory.

Sleep and memory — what stage helps what

  • Declarative (facts, words): consolidated during slow‑wave sleep (SWS / Stage 3).

  • Non‑declarative (motor skills, implicit): consolidated during REM (including naps that include REM).

  • Practical tip: study, then get adequate NREM SWS for facts; practice then get REM for skills.

Why we sleep (short list)

  • Conserve energy.

  • Adaptive safety (sleep timing shaped by environment/predators).

  • Restore brain/body (mental activity increases sleep need).

  • Memory consolidation (different stages support different memory types).

  • Development (REM important early in life).

Chemical control (what keeps you awake / makes you sleep)

  • Wake-promoting: Acetylcholine (basal forebrain), Histamine (TMN), Orexin (lateral hypothalamus), Norepinephrine (locus coeruleus), Serotonin (raphe nuclei).

  • Sleep‑promoting: GABA (SWS generator) and somnogens like adenosine (builds with brain use; blocked by caffeine).

  • Flip‑flop switch: VLPO (ventrolateral preoptic area) increases to promote sleep when somnogens accumulate.

REM control

  • REM‑on: sublateral dorsal nucleus (dorsal pons).

  • REM‑off: ventrolateral periaqueductal gray (vlPAG).
    (Balance of these toggles REM episodes.)

Common sleep disorders (quick)

  • Insomnia: transient or chronic; often environmental/hyperarousal; more common in women.

  • REM behavior disorder: REM without normal paralysis → acting out dreams.

  • Narcolepsy: sudden sleep attacks; often enter REM directly.

  • Cataplexy: sudden muscle paralysis triggered by strong emotion (conscious but immobile).

  • Cause note: narcolepsy often linked to loss of orexin neurons (autoimmune) or receptor mutations in animals.

Quick study/nap rules for ADHD-friendly use

  • For declarative learning (facts): aim for uninterrupted sleep that includes early-night SWS — even a 90–120 minute nap can help if it reaches SWS.

  • For skill learning: naps that include REM (longer naps or overnight sleep) boost performance.

  • To help sleep onset: reduce caffeine (blocks adenosine), dim lights/screens before bed, keep consistent schedule.

THIS IS KNOWT CONDENSED VERSION

One‑sentence summary

Sleep is an active, staged brain process (waves: beta → alpha → theta → delta) with NREM stages for restoration and SWS memory consolidation, and REM for dreaming and motor memory; chemicals like orexin and adenosine control wake/sleep balance, and disruptions cause insomnia, narcolepsy, or REM behavior disorder.

Fast facts

  • Sleep = active brain state; not unconscious.

  • Night structure: deep sleep early; REM later.

Brain waves

  • Beta 13–30 Hz — awake, active thinking.

  • Alpha 8–12 Hz — awake, resting.

  • Theta 4–7 Hz — sleep onset.

  • Delta < 3.5 Hz — deep, slow-wave sleep.

Two main sleep classes

  • NREM (non‑REM): three stages (light → deep).

  • REM: brain looks “awake”; vivid dreams; muscle paralysis.

NREM stages

  • Stage 1 (light): Alpha → Theta.

  • Stage 2 (light): Theta; sleep spindles (memory consolidation) & K‑complexes (block noise).

  • Stage 3 (slow‑wave / deep): Dominated by delta waves; hard to wake.

REM sleep

  • EEG: low‑amplitude, high‑frequency (looks awake).

  • Features: rapid eye movements, muscle paralysis, vivid/illogical dreams.

  • Critical for motor skill memory; mostly second half of night.

Sleep and memory

  • Declarative (facts): consolidated during slow‑wave sleep (SWS / Stage 3).

  • Non‑declarative (motor skills): consolidated during REM.

Why we sleep

  • Conserve energy, adaptive safety, restore brain/body, memory consolidation, development.

Chemical control

  • Wake-promoting: Acetylcholine, Histamine, Orexin, Norepinephrine, Serotonin.

  • Sleep-promoting: GABA (SWS generator), adenosine (builds with brain use, blocked by caffeine).

Common sleep disorders

  • Insomnia: difficulty sleeping.

  • REM behavior disorder: acting out dreams due to lack of paralysis.

  • Narcolepsy: sudden sleep attacks; often linked to orexin loss.

  • Cataplexy: sudden muscle paralysis by emotion (conscious).

Quick study/nap rules

  • For declarative learning (facts): aim for early-night SWS.

  • For skill learning: naps including REM boost performance.