A long list to help you with your in-depth sleep research.
Abdominal Movement - Indiagnostic sleep studies, abdominal movement is recorded. This is one of themeasures of respiratory effort, reflecting movement of the diaphragm.

Advanced Sleep PhaseSyndrome (ASPS) - Phases of the daily sleep/wake cycle are advanced withrespect to clock time.  This is classified as a circadian rhythmdisorder.   The sleep phase occurs well ahead of the conventionalbedtime and the tendency is to wake up too early.

Alpha rhythm - EEGoscillations, prominent over the occipital cortex, with a frequency of 8-13 Hzin adults;  indicative of the awake state; present in most, but not all,normal individuals;  most consistent and predominant during relaxedwakefulness.

Alpha intrusion - briefoccurrence of alpha activity during a stage of sleep.

Ambulatory Monitor -Portable system used to record (continuously) multiple physiological variablesduring sleep.

Apnea -Literally means "no breath";  the cessation of airflow at thenostrils and mouth for at least 10 seconds.

Apnea index (AI) - Ameasure of the severity of sleep apnea;  the number of apnea events perhour.

Apnea/Hypopnea index(AHI) - the number of apneas and hypopneas per hour. 5-20=mild,21-50=moderate, above 51 severe

Arousal -abrupt change from sleep to wakefulness, or from a "deeper" stage ofnon-REM sleep to a "lighter" stage

Arousal Disorder -parasomnia disorder presumed to be due to an abnormal arousal function. Classical arousal disorders:  sleepwalking, sleep terrors and confusionalarousals.

Arousal Threshold - easethat a sleeping person is awakened.

Arrhythmia -irregularity or absence of the heart rhythm caused by disturbances intransmission of electrical impulses through cardiac tissue.

Auto Adjusting ContinuousPositive Airway Pressure Device (SmartPAP) (Auto-PAP) - Atype of CPAP machine monitoring changes in breathing and compensatesautomatically by making appropriate adjustments in pressure.

Automatism -automatic action--especially any action performed apparently without intentionor awareness.

Basic Sleep Cycle -progression through orderly succession of sleep states and stages. For thehealthy adult, the first cycle is begins by going from wakefulness to non-REMsleep. The first REM period follows the first period of non-REM sleep, and thetwo sleep states continue to alternate throughout the night with an averageperiod of about 90 minutes. A night of normal human sleep usually consists of4-6 non-REM/REM sleep cycles.

Benzodiazepines -developed in the 1950's, this class of compounds tranquilize and sedates.

Beta Activity - brainwaves with a frequency of greater than 13 Hz (Hertz).

Bi-Level -Bi-level pressure device used to treat sleep apnea.  The "bi"refers to two pressures:  a lower pressure for exhalation and a higherpressure for inhalation.  Bi-Level machines are more expensive than astandard CPAP, but some patients tolerate it better because they can exhalecomfortably against the constant inhalation pressure. (Sometimes called Bi-PAP,but that is a trademark name of one system)

Biological Clock - termfor the brain process causing us to have 24-hour fluctuations in bodytemperature, hormone secretion, and other bodily activities. The most importantfunction fosters the daily alternation of sleep and wakefulness. The biologicalclock is found in a pair of tiny bilateral brain areas called thesuprachiasmatic nuclei.

Body Position - fourpositions are identified which a patient may be sleeping; back, left side,right side or abdomen. The time spent sleeping in each position and the numberof respiratory events in a particular position are tabulated.

Bradycardia - heartrhythm with a rate lower than 60 beats per minute in an adult.

Brain Waves – thebrain’s spontaneous electrical activity studied by electroencephalography(EEG).

Bruxism – teethgrinding during sleep

Cardiac Arrest -sudden cessation of the heart beat.

Cardiovascular -Pertaining to blood vessels  and the heart

Cataplexy -sudden, dramatic decrement in muscle tone and loss of deep reflexes that leadsto muscle weakness, paralysis, or postural collapse.  Usually caused byoutburst of emotion:  laughter, startle, or sudden physical exercise; oneof the tetrad of symptoms of narcolepsy.

Central apnea -absence of airflow and inspiratory effort;  apnea caused by irregularityin the brain's control of breathing.

Central Nervous System(CNS) - brain and spinal cord.

Cheyne-Stokes respiration -breathing pattern typified by regular "crescendo-decrescendo" orwaxing and waning fluctuations in respiratory rate and tidal volume.

Chronotherapy -treatment for circadian rhythm sleep disorder by systemically changing sleepingand waking times to reset the biological clock.

Circadian rhythm -innate, daily, fluctuation of behavioral and physiological functions, includingsleep waking, generally tied to the 24 hour day-night cycle but sometimes to adifferent (e.g., 23 or 25 hour) periodicity when light/dark and other time cuesare removed.

Compliance -adhering to or conforming with a regimen of treatment such as CPAP

CPAP - ContinuousPositive Airway Pressure;  the device used to treat sleepapnea by sending positive airway pressure at a constant, continuous pressure tohelp keep an open airway, allowing the patient to breathe normally throughhis/her nose and airway

CPAP Pressure -pressure needed to maintain an open airway in a sleep apnea patient treatedwith CPAP, expressed in centimeters of water (cm H20). The positive pressurecan range from 5 - 20 cm H20. Different patients require different pressures.The value is determined in a CPAP titration study.

Deep Sleep -refers to combined non-REM sleep stages 3 and 4 in sleep studies

Delayed sleep phase - Acondition occurring when the clock hour at which sleep normally occurs is movedback in time in a given, 24 hour sleep-wake cycle. The result is a temporarily displaced(delayed) occurrence of sleep within the 24 hour cycle.

Delta sleep -stage(s) of sleep in which EEG delta waves are prevalent or predominant (sleepstages 3 and 4, respectively).

Delta waves - EEGactivity with a frequency less than 4 Hz.  In human sleep stage scoring,conventionally the minimum criteria for scoring delta waves is 75 uV(peak-to-peak) amplitude, and 0.5 second duration (2 Hz).

Diagnostic Sleep Study -monitoring of several physiological activities in a sleeping individual. Usuallyperformed to determine the absence or presence of a specific sleep disorder.The sleep study can occur in a sleep disorders center or in a patient's homewith portable recording equipment.

Diaphragm -large, concave muscle attached to the rib cage at bottom of the chest (top ofthe abdomen). Inhalation occurs when diaphragm contracts. Exhalation is passiveas the muscle relaxes.

Diurnal -active and wakeful in the daytime versus active in the nighttime

DME - Durable MedicalEquipment. Equipment such as wheelchairs and walkers which areprescribed for use by or on the order of a physician, also includes CPAP andBI-Level machines.

Drowsiness, Drowsy- quiet wakefulness occurring prior to sleep onset.

Dyssomnia - adisorder of sleep or wakefulness; not a parasomnia

Electrocardiography (EKG) – amethod of measuring the electrical activity of the heart.

Electrodes - smalldevices transmitting biological electrical activity from subject to polygraph

Electroencephalogram(EEG) - recording through the scalp of electrical potentials from the brainand the changes in these potentials. The EEG is one of the three basicvariables (along with the EOG & EMG) used to score sleep stages and waking.Surface electrodes are used to record sleep in humans, recording potentialdifferences between brain regions and a neutral reference point, or betweenbrain regions.

Electromyogram (EMG) -recording of electrical activity from the muscular system; in sleep recording,synonymous with resting muscle activity or potential. The chin EMG, along withEEG and EOG, is one of the three basic variables used to score sleep stages andwaking. Surface electrodes are used to record sleep in humans, measuringactivity from the submental or masseter muscles. These reflect the changes inresting muscle activity.  During REM sleep the chin/cheek EMG is tonicallyinhibited.

Electro-oculogram (EOG) -recording of voltage changes resulting from shifts in position of theeyeball-possible because each globe is a positive (anterior) and negative(posterior) dipole; along with the EEG and the EMG, one of the three basicvariables used to score sleep stages and waking. Human sleep recordings utilizesurface electrodes placed near the eyes to record the movement of the eyeballs.Rapid eye movements in sleep indicate a certain stage of sleep ( usually REMsleep).

ENT - Ear,Nose and Throat.  A doctor specializing in diseases of the Ear, Nose andThroat.  These specialists often do surgery as well, and may be referredto as an ENT surgeon.

EPAP - ExpiratoryPositive Airway Pressure. Pressure prescribed for the expiratory (breathingout) phase of an individual on Bi-level CPAP therapy for OSA (obstructive sleepapnea).

Epidemiology -Scientific discipline studying the incidence, distribution, and control ofdisease in a population. Includes the study of factors affecting the progressof an illness, and, in the case of many chronic diseases, their naturalhistory.

Epoch - Astandard 30 second duration of the sleep recording that is assigned a sleep stagedesignation; for special purposes, occasionally longer or shorter epochs arescored.

Epworth Sleepiness Scale - indexof sleep propensity during the day as perceived by patients, and derived fromthe answers to 8 questions.

Esophageal Pressure - measurementused to determine respiratory effort and by inference, airway resistance.Considered an invasive measure, generally used only in polysomnographictesting, conducted in sleep disorders centers.

Excessive daytimesleepiness or somnolence (EDS) -  subjective report ofdifficulty in staying awake, accompanied by a ready entrance into sleep whenthe individual is sedentary

Expiratory Phase - airis expelled during this phase of the breathing cycle

Fatigue -feeling of tiredness or weariness usually associated with performancedecrements

FiberopticNasopharyngoscope - flexible fiberoptic scope used in theexamination of nasal passages, pharynx, hypopharynx and larynx.

Fibromyalgia - adisease syndrome whose primary symptoms are muscle pain and fatigue.

Flattening Index -number indicating the amount of airflow limitation caused by partial closure ofthe upper airway. 0.3 indicates an open airway, 0.15 is mildly obstructed, 0.1is severely limited airflow, and 0.0 reflects a totally closed airway.  FlatteningIndex is used to identify the condition known as Upper Airway ResistanceSyndrome (UARS), and is continuously recorded in both diagnostic sleep studiesand CPAP titrations.

Flow Limitation – thepartial closure of the upper airway impeding the flow of air into the lungs.

Forbidden Zone – theperiod of strongest clock-dependent alerting, usually in the evening. Preventsfalling asleep.

Fragmentation (pertainingto Sleep Architecture) - interruption of a sleep stage as a result ofthe appearance of a lighter stage, or to the occurrence of wakefulness, whichleads to disrupted non-REM-REM sleep cycles.

GABA (Gamma-AmniobutyricAcid) - major neurotransmitter in the brain, which is considered to beinvolved in muscle relaxation, sleep, diminished emotional reaction andsedation.

Gastroesphageal RefluxDisease (GERD) - flow of stomach acid upwards into the esophagusthat can cause arousals and disrupt sleep.

Genioglossus tongueadvancement – a possible surgical treatment used for sleepapnea and/or snoring, improving the airway behind the base of the tongue. Thegenioglossus, the main tongue muscle, relaxes during sleep, often allowing thetongue to fall into the airway. The muscle attaches to the middle of the lowerjaw.  A segment of bone containing this muscle is pulled forward andstabilized, opening the airway space behind the tongue.

Habitual Snorers - thosewho snore nearly every night

Heart Rate or beats perminute (bpm) – pace/speed of the heart measured in beats perminute. 60-80 is considered normal in adults.

Hertz (Hz) - unitof frequency; equal to cycles per second (cps).

Histogram (sleep) - graphindicating sleep stages thoughout the night.

Humidification -moisture is added to the airflow as an adjunct to CPAP (Continuous PositiveAirway Pressure) therapy in treating obstructive sleep apnea (OSA).Humidification can be added to the CPAP by diverting the airflow over orthrough a cool or heated water reservoir (humidifier) to prevent the upperairway from drying out.

Hyoid Suspension – apossible surgical procedure sometimes used in the treatment of sleep apneaand/or snoring, designed to improve the airway behind the base of the tongue.The hyoid bone is located in the neck where some tongue muscles attach. Thehyoid bone is pulled forward in front of the voice box and can open the airwayspace behind the tongue.

Hyperactivity –typical behavior in a child with a sleep disorder which is causing lack ofquality sleep

Hypercapnia –excessive or elevated carbon dioxide in the blood

Hyperirritability -Extreme irritability; seen in sleep deprived subjects.

Hypersomnia –excessive, prolonged sleep

Hypertension -Highblood pressure.

Hypnagogic imagery(-hallucinations) - Vivid sensory images occurring at sleep onsetbut particularly vivid with sleep-onset REM periods;  feature ofnarcoleptic REM naps.

Hypnagogic startle -"sleep start" or sudden body jerk, observed normally just at sleeponset, resulting in at least momentary awakening

Hypnophobia -Morbid fear of falling asleep.

Hypnotics -Sleep-inducing drugs.

Hypopharynx -lowermost portion of the pharynx leading to the larynx and esophagus.

Hypopnea -shallow breathing in which the air flow in and out of the airway is less thanhalf of normal--usually associated with oxygen desaturation.

Hypoventilation -reduced rate and depth of breathing.

Hypoxemia -abnormal lack of oxygen in the blood in the arteries.

Hypoxia -deficiency of oxygen reaching the tissues of the body.

Imidazopyridines - Newclass of compounds inducing sleepiness. (Zolpidem, trade name Ambien, is inthis class).

Inappropriate SleepEpisodes – unplanned sleep periods often occuring in an unsafe situation (i.e.,while driving). These episodes are always due to sleep deprivation.

Insomnia – complaintdescribing difficulty in sleeping

Inspiratory Phase - partof the breathing cycle in which air is inhaled.

Invasive –referring to a medical procedure in which a bodily orifice or the skin must bepenetrated for the purpose of collecting data, or for diagnosing or treating adisorder

IPAP -Inspiratory Positive Airway Pressure.  Physician prescribed pressure forthe inspiratory phase on a Bi-level CPAP device, used in the treatment of OSA.

Jet Lag -disturbance induced by a major rapid shift in environmental time during travelto a new time zone

K-Alpha - typeof microarousal;  K complex followed by several seconds of alpha rhythm.

K complex -sharp, negative, high-voltage EEG wave, followed by a slower, positivecomponent. K complex, occurring spontaneously during NREM sleep, beginning in(and defining) stage 2.  K complexes can be elicited during sleep byexternal (particularly auditory) stimuli as well.

Laser assisteduvulopalatoplasty (LAUP) - can eliminate or decrease snoring buthas not been shown to be effective in the treatment of sleep apnea.

Leg Movement - Legmovements are recorded in both diagnostic sleep studies and titration studies.

Letter of MedicalNecessity (LMN) - certification by a physician that the prescribeditem(s) is/are medically indicated, reasonable and necessary with reference tothe standards of medical practice and treatment of a patient's condition

Light-Dark Cycle -periodic pattern of light (artificial or natural) alternating with darkness

Light Sleep - termused to describe non-REM sleep stage 1, and sometimes, stage 2.

Light Therapy - usedin the treatment of SAD (Seasonal Affective Disorder) and other conditions.Exposes the eyes to light of appropriate intensity and duration and at theappropriate time of day to effect the timing, duration and quality of sleep.

Limit-Setting SleepDisorder – disorder due to child’s difficulty in fallingasleep by delaying and refusing to go to bed

Linear Sleepiness RatingScale - measure of subjective sleepiness.  The scale contains ahorizontal line, 100 mm in length --the right extreme is labeled "VerySleepy" and the left extreme is labeled "Very Wide Awake."

Macroglossia - largetongue; usually a congenital disorder (present at birth)

Maxillofacial -pertaining to the jaws and face.

Mandibular MaxillaryOsteotomy and Advancement (MMOA) - procedure developed forpatients with retrolingual obstruction, patients with retropalatal andretrolingual obstruction who have not responded to CPAP anduvulopalatopharyngoplasty (UPPP).

Melatonin -hormone secreted by the brain’s pineal gland

Micro-arousal -partial awakening from sleep

Micro-sleep -period lasting up to a few seconds during which the polysomnogram suddenlyshifts from waking characteristics to sleep.

Mixed (sleep) apnea -interruption in breathing during sleep beginning as a central apnea thenbecoming an obstructive apnea.

Monocyclic - asingle major sleep period and a single major wake period in a 24-hour day.

Motor Activity in Sleep - anymuscular movement during sleep

Motor Atonia – theabsence of muscle activity during sleep

Movement arousal - bodymovement associated with arousal or awakening; a sleep scoring variable.

Movement time - termused in sleep record scoring to denote when EEG and EOG tracings are obscuredfor more than 15 seconds due to movement.

Multiple sleep latencytest (MSLT) - a series “nap tests” utilized in the assessmentof excessive daytime sleepiness.

Muscle Tone –amount of tension in a muscle.

Myoclonus - musclecontractions in the form of "jerks" or twitches.

Nap - shortperiod of planned sleep generally obtained at a time separate from the majorsleep period.

Narcolepsy - sleepdisorder characterized by excessive sleepiness, cataplexy, sleep paralysis, hypnogogichallucinations, and an abnormal tendency to pass directly from wakefulness intoREM sleep

Nasal Airflow/NasalVentilation - recording of the complete respiratory cycle bymeasuring inspiratory and expiratory airflow

National Commission onSleep Disorders Research (NCSDR) - the commission (created bythe U.S. Congress in 1990) conducted a comprehensive study of the social andeconomic impact of sleep disorders in America and made recommendations based onits findings to the Congress in January 1993

Neurology -branch of medicine that referring to the nervous system and its diseases

Neurotransmitters -endogenuous chemical components that are released from axon terminals of oneneuron and transmit the signal to the next neuron by combining with itsreceptor molecules.  Neurotransmitters important in the control of sleepand wakefulness include: norepinephrine, serotonin, acetylcholine, dopamine,adrenaline and histamine.

Nightmare -unpleasant and/or frightening dream occurring in REM sleep (different from anight terror)

Night Terrors - alsoknown as sleep terrors, or pavor nocturnus.  Night terrors arecharacterized by an incomplete arousal from slow wave sleep.  If, theindividual is awakened during a night terror, he/she is usually confused anddoes not remember details of the event.  Night terrors are different fromnightmares; if an individual is awakened during a nightmare, he/she functionswell and may have some recall of the nightmare.

Nocturia -excessive, often frequent, urination during the night

Nocturnal -"Of the night;" pertaining to events happening during sleep or thehours of darkness.

Nocturnal Confusion -episodes of delirium and/or disorientation near or during nighttime sleep;often seen in victims of Alzheimers Disease and more common in the elderly

Nocturnal sleep-relatedeating disorder (NS-RED)- Getting up during the night and eatingwhile sleepwalking. No recall in the morning.

Nocturnal Enuresis(Bedwetting) - urinating while asleep

Non-Invasive -Medical procedure not penetrating the skin or a body cavity.

NREM or non-REM sleep -characterized by slower and larger brain waves and little or no dreambehavior;  quiet sleep, slow-wave sleep;  approximately 80% of sleep

NREM Sleep Intrusion - briefperiod of NREM sleep patterns appearing in REM sleep;  a portion of NREMsleep not appearing in its usual sleep cycle position

Obesity-HypoventilationSyndrom> - term applied to obese individualshypoventilating during wakefulness.

Obstructive apnea -cessation of airflow (at least 10 seconds) in the presence of continuedinspiratory effort;  cessation of breathing during sleep, due to amechanical obstruction, such as a semi-collapsed trachea, tongue relaxed toback of the throat, or a large among of tissue in the uvula area.

Obstructive Hypopnea -periodic and partial closure of the throat during sleep resulting in reducedair exchange at the level of the mouth and/or nostril.

Ondine's Curse - the respiratorycenter in the brain is unable to stimulate breathing in response to anincreased amount of carbon dioxide in the blood.  Ondine's Curse orcentral alveolar hypoventilation typically worsens during sleep.

Optimum Sleep -average amount of sleep needed every night by an individual.

Oxygen Desaturation - lessthan normal amount of oxygen carried by hemoglobin in the blood;  valuesbelow 90% are considered abnormal

Oxygen Saturation -measure of oxygen carried by hemoglobin in the blood. Normal values 90% - 100%.

Oximeter (Pulse) - givesestimates of arterial oxyhemoglobin saturation (SaO2) by utilizing selectedwavelengths of light to non invasively determine the saturation ofoxyhemoglobin (SpO2)

Oximetry (Pulse) -continuous monitoring of oxygen saturation of arterial blood from a pulseoximeter;  the sensor is usually attached to the finger.

O2 -Chemical symbol for oxygen. Criterion lowest percent O2 saturation: Greaterthan 85%=mild, 80% to 85%=moderate, less than 80%=severe

Parasomnia - anevent happening during sleep, or induced or exacerbated by sleep, such assleepwalking or asthma; not a dyssomnia.

Paroxysmal nocturnaldyspnea (PND) - respiratory distress and shortness of breath dueto pulmonary edema, appearing suddenly and often awakening the sleepingindividual.

Pathological Sleep -abnormal sleep patterns.

Pavor Nocturnus (NightTerrors) - See Night Terrors.

Perceptual Disengagement -change in consciousness at the onset of sleep when environmental stimuli are nolonger perceived, and there is no longer any conscious, meaningful interactionwith the environment.

Periodic Breathing -repetitive apneic pauses, common in premature infants.

Periodic Limb MovementDisorder - also known as periodic leg movements and nocturnal myoclonus.Characterized by periodic episodes of repetitive and highly stereotyped limbmovements occuring during sleep. The movements are often associated with apartial arousal or awakening; however, the patient is usually unaware of thelimb movements or frequent sleep disruption.  Between the episodes, thelegs are still. There can be marked night-to-night variability in the number ofmovements or in the existence of movements.

Persistent Insomnia -continuing insomnia responding poorly to treatment.

Pharynx - areaposterior to the nares and the oral cavity;  passageway for air from thenasal cavity and/or the mouth to the lungs via the larynx and the trachea, forfood and liquids from the mouth to the esophagus

Phase advance -movement to a position earlier in the 24 hour sleep - wake cycle of a period ofsleep or wake; for example, a shift of the sleep phase from 11 p.m. - 7 a.m. to8 p.m. - 4 a.m.

Phase delay - Phasedelay is exactly the opposite of phase advance, i.e., a shift later in time.

Phasic (Event/Activity) -brain, muscle, or autonomic related event of a brief and episodic natureoccurring in sleep. Usually  occur during REM sleep, such as eye movementsand/or muscle twitches

Photoperiod -duration of light in a light/dark cycle.

Pickwickian Syndrome -obesity accompanied by somnolence, lethargy, chronic hypoventilation, hypoxia,and secondary polycythemia (a condition marked by an abnormal increase in thenumber of circulating red blood cells);  usually has severe obstructive sleepapnea

Pineal Gland - glandin the brain secreting the hormone melatonin.

PLMD-Arousal Index -number of sleep-related periodic leg movements per hour of sleep that areassociated with an EEG arousal

Polycyclic -multiple sleep periods and wake periods in a 24-hour day.

PO2 -partial pressure of oxygen (O2) in the blood. A value above 60 is usuallyconsidered a safe level:  lower than 60 indicated hypoxemia and potentialdanger for the patient.

Polysomnogram (PSG) -continuous and simultaneous recording of physiological variables during sleep,i.e., EEG, EOG, EMG (the three basic stage scoring parameters), EKG,respiratory air flow, respiratory excursion, lower limb movement, and otherelectrophysiological variables.

Polysomnograph

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