Topic 1.5 - Sleeping & Dreaming

Sleep

Periodic, natural loss of consciousness

Circadian Rhythm

Body’s biological clock that syncs with the 24-hour day and night cycle

Alpha Waves

Brian activity when body is awake but in a relaxed state just before sleep

NREM

Non-rapid eye movement

NREM-1

First stage; brief stage where hypnagogic sensations may be experienced

Hypnagogic Sensations

Floating/falling sensations

NREM-2

Second stage; longest stage characterized by sleep spindles

Sleep Spindles

Burst of rapid, rhythmic brainwave activity

NREM-3

Third stage; 20-25% of night characterized by deep sleep and slow delta waves (slow, high amplitude)

REM

rapid eye movement

REM Sleep

Fourth stage; characterized by vivid dreams, increased heart rate, and muscle paralysis

Suprachiasmatic Nucleus

Pair of cell clusters in the hypothalamus that control circadian rhythm, signaled by light

Recuperation

Helps restore immune system and repair brain tissue (neurons)

Restoration

Consolidates our memories by replaying recent learning + strengthening neural connections

Supports growth

Human growth hormone released by pituitary gland during sleep

Information-Processing Theory

Dreams may help sift, sort, and fix the day’s experiences in our memory

Physiological Function Theory

Dreams provide brain with stimulation, preserving and expanding its neural pathways

Activation-Synthesis Theory

Dreams are brain’s attempt to synthesize random neural activity

Cognitive Development Theory

Dreams are part of brain maturation and cognitive development

Insomnia

Persistent problems falling/staying asleep

Narcolepsy

Sudden attacks of overwhelming sleepiness, usually lasting less than 5 mins

• skips NREM and falls straight into REM

Sleep Apnea

Intermittently stop breathing during sleep

Sleepwalking

(Somnambulism) walking/performing tasks while asleep

• usually harmless, occurs during NREM-3

REM Sleep Behavior Disorder

Normal REM paralysis doesn’t occur, instead twitching, talking, etc; often acting out one’s dreams