Glossary of Terms
Terms used in sleep medicine:
A biomedical instrument used to measure body movement.
Equivalent to REM sleep used in ontogenetic and phylogenetic literature.
EEG frequency of 8-12 Hz.
Alpha wave occurring in Slow Wave Sleep.
A brief superimposition of alpha wave in various sleep stages.
EEG frequency of 8-12 Hz predominantly found in Occipital cortex during relaxed wakefulness with eyes closed.
Cessation of oro-nasal airflow for 10 seconds or more during any sleep stage.
Number of apneic events per hour of sleep.
Abrupt change of EEG frequency for at least 3 seconds occurring in any sleep stage.
More than 15 seconds of wakefulness during any epoch of sleep stage.
Type of parasomnia involving abnormal arousal mechanism from sleep.
Typical or normal state of an investigative variable before experimental manipulation.
Clock time when one attempts to fall asleep, as differentiated from clock time when one gets into bed.
EEG activity greater than 13 cycles per second associated with alert wakefulness.
Teeth grinding during sleep.
Sudden loss of skeletal muscle tone and deep tendon reflexes causing postural collapse usually seen in narcoleptic patients.
Cheyne Stokes Respiration
Breathing pattern characterized by regular waxing and waning of respiratory rate and tidal volume.
Internal biological clock of sleep wake functions generally tied to 24-hour dark-light cycle.
Type of psychophysiological insomnia produced by the development, during an earlier experience of sleeplessness.
Rhythmic fluctuation of one maximum or minimum to the next.
Deep or Delta Sleep
Common term for stage 3 and 4 sleep.
Delayed Sleep Phase
A circadian rhythm sleep disorder delaying normal sleep wake cycle.
EEG wave of .5 to 2 cycles per second, .5 second in duration and greater than 75 microvolt amplitude.
Commonly denotes arterial oxygen desaturation.
Pertaining to the daytime.
A primary disorder of initiating and maintaining sleep or of excessive sleepiness.
End-Tidal Carbon Dioxide
CO2 value determined at the nostrils by an infrared gas analyzer.
Synchronization of a biological rhythm by a forcing stimulus such as environmental time cue.
A measure of duration of sleep recording that is typically of 20 or 30 seconds duration.
Excessive Daytime Sleepiness
Usually subjective report of excessive and uncontrollable sleepiness at inappropriate time.
Extrinsic Sleep Disorders
Sleep disorders either originates, develops or arises from outside of the body.
Amount of wakefulness that occurs after the final wake-up time until lights on.
First Night Effect
Altered sleep physiological variables due to unfamiliar sleeping environment and recording apparatus, commonly found in subjects in a sleep laboratory on the first night.
Repeated arousals and/or awakenings causing interrupted sleep.
Free Running Condition
Natural endogenous biological rhythm when environmental time cues are removed.
Unit of frequency denoting cycles per second.
Elevated carbon dioxide level in blood.
Synonym to excessive sleepiness.
NREM-REM sleep stages and cycles forming the infrastructure of sleep plotted in the form of histogram
Occurrence of hallucination during transition from wakefulness to sleep or sleep onset.
Occurrence of hallucination during transition from sleep to wakefulness or sleep offset.
Referred to 50% reduction of oro-nasal airflow for 10 seconds or more during sleep, usually associated with an arousal and/or oxygen desaturation.
Difficulty in initiating and/or maintaining sleep.
A K-complex followed by several seconds of alpha rhythm; a type of micro arousal.
A sharp, negative EEG wave followed by sharp positive wave, duration of at least .5 seconds and amplitude of 50 microvolts.
Usually refereed to stage-1 sleep.
Major Sleep Episode
The longest sleep episode that occurs during habitual sleeping time.
An episode lasting up to 10 seconds during which external stimuli are not perceived.
Particular arrangement of sleep derivatives displayed simultaneously in polysomnogram.
Muscle contractions in the form of abrupt jerks or twitches.
A short sleep episode occurring during habitual wakefulness.
Respiratory distress during nighttime.
Synonymous with REM sleep.
Abnormal behaviors or activities occurring during sleep.
Phenomenon of abrupt onset, attain maximum and termination suddenly.
Brief and episodic eye movements during REM sleep.
A term applies to an individual who snores and had alveolar hypoventilation syndrome.
Term used to describe NREM sleep in in infants.
REM Sleep Onset
Commencement of REM sleep.
REM Sleep Latency
Interval from sleep onset to REM sleep onset.
Increased frequency, duration and percentage of REM sleep commonly seen after REM sleep deprivation and during CPAP titration.
Respiratory Disturbance Index: Number of all apneas and hypopneas per hour of total sleep time.
Saw Tooth Waves
Notched appearance of EEG waves of 3 to 7 cycles per second occurring during REM sleep.
NREM-REM sleep stages and cycles forming the infrastructure of sleep, often plotted in the form of histogram.
A daily written record or log of a person’s sleep-wake pattern.
Synonymous with NREM-REM cycle.
Proportion of total sleep time and time in bed.
Conditions and practices that promote continuous and effective sleep.
Duration of time from lights off to sleep onset.
Transition from wakefulness to sleep after lights off.
Imaginary and thinking experienced during sleep.
Immobilty of body at sleep offset as a manifestation of REM sleep in narcoleptic patients.
Spindle shaped EEG bursts of 12 to 14 cycles per second lasting .5 to 1.5 seconds and of 50 microvolt amplitude.
Type of parasomnia causing sleep walking.
EEG wave of 3 to 7 cycles per second seen in stage-1 and REM sleep.
Total Sleep Time
Amount of MREM and REM sleep between lights off and lights on.
EEG pattern of sleeping newborn, characterized by bursts of slow waves, intermixed with sharp waves and intervening period of relative quite period of low-amplitude activity.
Hardening and expansion of penis associated with REM sleep.
Sharp negative EEG wave of high amplitude usually occurring during stage-1 sleep.
Environmental time cue that usually helps to entrain biological clock.
Abbreviations used in sleep medicine:
Cm of H2O
Epworth Sleepiness Scale
Stanford Sleepiness Scale
Centemeter of Water
High Frequency Filter
Low Frequency Filter
Cycle per second
Nasal Continuous Positive Airway Pressure
Inspiratory Positive Airway Pressure
Expiratory Positive Airway Pressure
Bilevel Positive Airway Pressure
Multiple Sleep Latency Test
Maintenance of Wakefulness Test
Nocturnal Penile Tumescence
Positive Airway Pressure
Excessive Daytime Sleepiness
Obstructive Sleep Apnea
Central Sleep Apnea
Periodic Limb Movements Disorder
Restless Leg Syndrome
Rapid Eye Movement
Non Rapid Eye Movement
Slow Wave Sleep
Sleep Disordered Breathing
Chronic Obstructive Pulmonary Diseases
Premature Ventricular Contraction
Premature Atrial Contraction
Apnea Hypopnea Index
Respiratory Disturbance index
American Sleep Disorders Association
Association of Polysomnographic Technologist
Board of Registered Polysomnographic Technologist
Central Nervous System
Cycles per Second
Disorder of Initiating and Maintaining Sleep
Diagnostic and Statistical Manual
International Classification of Sleep Disorders
Fractional Inspired Oxygen
Oxygen Saturation Measured by Pulse Oxymeter
Paroxysmal Nocturnal Dystonia
Total Sleep Time
Cheyne Stokes Respiration
End Tidal Carbon Dioxide
Transcuteneous Carbon Dioxide