Wk 1 Lecture 2, Sleep Stages and Polysomnography

Polysomnography

The gold standard measure of sleep that records various physiological signals during sleep.

Sleep Architecture

Refers to the basic structural organization of normal sleep, with each sleep stage having unique EEG characteristics.

NREM

Non-Rapid Eye Movement sleep, which consists of three stages (N1, N2, N3) before transitioning to REM sleep.

REM Sleep

Rapid Eye Movement sleep, characterized by increased brain activity and vivid dreaming.

Sleep Cycle

The pattern of sleep that includes multiple cycles throughout the night, typically lasting around 90 minutes.

Sleep Stages

States of consciousness during sleep, including stages N1, N2, N3 (NREM) and REM.

EEG (Electroencephalography)

A method used to measure electrical activity in the brain to define sleep stages.

Hypnic Jerks

Involuntary muscle contractions that may occur during the transition from wakefulness to sleep.

Sleep Efficiency

Calculated as total sleep time divided by total time in bed, indicating how effectively sleep is achieved.

Sleep Latency

The time it takes to transition from full wakefulness to sleep.

Type 1 Polysomnography

An attended, in-laboratory sleep study using at least seven channels for comprehensive sleep assessment.

Type 2 Polysomnography

An unattended, home sleep study that also uses at least seven channels for sleep measurement.

Type 3 Polysomnography

Limited channel monitoring of breathing parameters without sleep assessment, typically using four channels.

Type 4 Polysomnography

Limited channel monitoring with only 1-2 channels, typically measuring oximetry and possibly airflow.

Cough Reflex Suppression

The reduction or absence of the cough reflex during sleep stages, particularly in NREM sleep.

Physiological Signals

Various bodily measures recorded during polysomnography, such as EEG, EOG, EMG, ECG, and measures of airflow.

Growth Hormone

A hormone released during deep sleep (Stage N3) that promotes growth and repair.

Sleep Disorders

Conditions that disrupt normal sleep patterns, often diagnosed through polysomnography.

Dynamic Behavior of Sleep

The understanding of sleep as a complex activity controlled by various mechanisms in the brain.

Transition Period

The phase from wakefulness to sleep, particularly associated with Stage N1.