Sleep and Conciousness

N1

The very lightest stage of sleep,

the transition from wakefulness.

Theta waves, hypnic jerks.

N2

The stage where true sleep is established;

body temperature and heart rate drop.

appearance of Sleep Spindles and K-Complexes.

N3 (Deep Sleep / SWS)

The most restorative stage of sleep, difficult to wake from.

Defined by slow, high-amplitude Delta waves.

Delta Waves

The slowest, highest-amplitude brain waves

Sleep Spindles & K-Complexes

Distinct, rapid burst of rhythmic brain activity and a sharp, solitary high-amplitude wave, define NREM Stage N2.

HGH Release

The large pulses of Human Growth Hormone that occur primarily during NREM Stage N3,

define NREM Stage N2.

Paradoxical Sleep

An alternative term for REM sleep because the brain is highly active (Beta waves), but the body is motionless.

Atonia

The active, temporary paralysis of skeletal muscles during REM sleep, preventing the sleeper from acting out dreams.

REM Rebound

The phenomenon of experiencing longer and more frequent REM periods after a period of deprivation or suppression.

Emotional Memory Processing

A primary function of REM sleep; the process of stripping the raw affective (emotional) charge from new memories for stable retention.

Acetylcholine (ACh)

A key 'REM-on' neurotransmitter responsible for initiating and maintaining the high cortical activity of REM.

Declarative Memory

The type of memory consolidated during NREM Stage N3; includes facts, dates, and events.

Synaptic Homeostasis Hypothesis (SHY)

The leading theory that sleep's purpose is to downscale the overall strength of synapses (NREM) to re-optimize learning capacity (REM).

Synaptic Downscaling

The process during NREM deep sleep where the brain broadly reduces synaptic strength to clear neural 'clutter' and reduce the metabolic cost of maintaining all the day's connections.

The Shifting Cycle

The pattern where the first half of the night is dominated by restorative NREM N3, and the second half is dominated by REM for memory integration.

Circadian Rhythm

Our biological clock, regular cycles of flucations that occur in our bodies over 24hrs

Changes in body temp throughout the day

(How our body temp changes throughout the day)

Early morning: temp rises

Midday: temp peaks

Early afternoon: temp dips down

Evening: temp continues to drop

Hypnogogic sensation

The feeling of falling as you are almost asleep