Revision Unit 4 - AOS 1: Sleep, Consciousness and Circadian Rhythms

Vocabulary flashcards covering key terms from the lecture notes.

Consciousness

The awareness of one's own internal mental processes and the external world.

Normal waking consciousness (NWC)

A state of awareness during daily activities, with regular attention to internal and external environments.

Altered state of consciousness (ASC)

A state that differs in awareness from normal waking consciousness.

Sleep

A naturally occurring and reversible altered state of consciousness with reduced awareness and distinctive brain activity.

NREM sleep

Non-rapid eye movement sleep; three stages; about 80% of sleep; gradual decline in physiological activity.

REM sleep

Rapid eye movement sleep; brain activity increases while the body is externally calm; dreams commonly occur; about 20–25% of sleep.

N1 (Transitional Sleep)

Light sleep with decreased arousal; easily awoken; hypnic jerks; lasts about 5 minutes.

N2 (Light Sleep)

Continued lowering of bodily functions; eye movements stop; sleep spindles occur; lasts ~10–25 minutes; majority of sleep time.

N3 (Deep Sleep)

Deep sleep with lowest body functions; no eye or muscle movement; slowest brain waves; hard to wake; ~20–40 minutes in first cycle.

Sleep spindles

Brief bursts of rapid brain activity during N2 sleep.

Hypnic jerks

Involuntary muscle jerks occurring at sleep onset.

Paradoxical sleep

Another term for REM sleep; brain/body are active while externally calm.

Polysomnography

A multi-parameter sleep study using EEG, EOG and EMG to diagnose sleep disorders.

Electroencephalography (EEG)

Technique that detects brain electrical activity; four main waves: alpha, beta, theta and delta.

Electromyography (EMG)

Technique that detects skeletal muscle activity; measures muscle tone and movements during sleep.

Electro-oculography (EOG)

Technique that detects eye movements; helps determine sleep onset and REM.

Sleep diary

Subjective self-report tool to track sleep-wake patterns.

Video monitoring

Sleep study method collecting visual and audio information about a person’s sleep.

Circadian rhythm

Biological processes that operate on a roughly 24-hour cycle, influenced by internal and external cues.

Ultradian rhythm

Biological cycles shorter than 24 hours (e.g., a 90-minute sleep cycle).

Suprachiasmatic Nucleus (SCN)

Master body clock in the hypothalamus; regulates sleep-wake based on light cues and zeitgebers.

Melatonin

Hormone from the pineal gland that promotes sleepiness; levels rise in darkness.

Zeitgebers

Environmental cues (light, temperature, eating patterns) that synchronize circadian rhythms.

Bright light therapy

Treatment using exposure to bright light to reset the sleep-wake cycle.

Sleep hygiene

Sleep-promoting behaviours and environmental conditions (wind-down routine, dark/cool room, limit caffeine).

Circadian sleep disorders

Disorders where the circadian rhythm and sleep-wake schedule are misaligned.

Delayed Sleep Phase Syndrome (DSPS)

Circadian disorder with a delay in sleep onset and waking by 2+ hours; diagnosed after 3 months.

Advanced Sleep Phase Disorder (ASPD)

Circadian disorder with an advance in sleep onset and wake times (e.g., 6–8 pm to 1–3 am); more common in older people.

Shift work sleep disorder

Circadian rhythm sleep disorder due to non-standard work hours; insomnia and sleepiness; linked to health and safety risks.

Sleep deprivation

Not getting enough sleep in quality or quantity; total (no sleep) or partial (insufficient) deprivation.

Microsleeps

Brief episodes of sleep lasting a few seconds during wakefulness.

Affective functioning

Experience and regulation of emotions; sleep deprivation can cause irritability, anxiety and depressed mood.

Cognitive functioning

Mental processing such as memory, attention and problem solving; impaired by sleep deprivation.

Memory consolidation

Process by which sleep stabilizes and integrates daily information into long-term memory.

Repair and restoration theory of sleep

Idea that sleep supports bodily repair and restoration.

Sleep efficiency

Percentage of time in bed spent asleep.

Blood Alcohol Concentration (BAC)

Percentage of alcohol in the bloodstream; legal driving limit around 0.05; wakefulness effects can resemble sleep deprivation.

Dawson and Reid (1997) findings

Fatigue from sleep deprivation at a moderate level produces effects similar to alcohol intoxication; 17 hours awake ≈ BAC 0.05; 24 hours awake ≈ BAC 0.10.