Polysomnography - Citizendia

See also: Polysomnogram

Polysomnographic record of REM Sleep . EEG highlighted by red box. Eye movements highlighted by red line.

Polysomnographic record of REM Sleep . Polysomnogram (PSG is a multi-channel ("poly" recording ("gram" during sleep ("somno" resulting from a sleep test Polysomnography. EEG highlighted by red box. Eye movements highlighted by red line.

Polysomnography or PSG is a multi-parametric test used in the study of sleep; the test result is called a polysomnogram. In Mathematics, Statistics, and the mathematical Sciences a parameter ( G auxiliary measure) is a quantity that defines certain characteristics Sleep is a Natural state of bodily rest observed throughout the animal kingdom Polysomnogram (PSG is a multi-channel ("poly" recording ("gram" during sleep ("somno" resulting from a sleep test Polysomnography. The name is derived from Greek and Latin roots: 'poly' (many, Greek), 'somnus' (sleep, Latin), and 'graphein' (to write, Greek). Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome.

Normal patterns of human sleep were first discovered by Loomis, Harvey and Hobart in 1935. The discovery and documentation of REM (Rapid Eye Movement) sleep was accomplished by William C. Dement, Eugene Aserinsky, Nathaniel Kleitman and graduate students at the University of Chicago in the 1950s. William C Dement (born 1928 is a pioneering US Sleep Eugene Aserinsky (1921 &ndash 22 July 1998) was a graduate student at University of Chicago in 1953 when he discovered REM sleep. Nathaniel Kleitman ( April 26, 1895 &ndash August 13, 1999) was Professor Emeritus in Physiology at the University The University of Chicago is a Private university located principally in the Hyde Park neighborhood of Chicago. The 1950s Decade refers to the years of 1950 to 1959 inclusive It has since been codified by the adoption in 1968 of A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Stages of Human Subjects, edited by Allan Rechtschaffen and Anthony Kales. Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. Allan Rechtschaffen is a noted pioneer in the field of Sleep research whose work includes some of the first laboratory studies of Insomnia, Narcolepsy,

Aserinsky and Kleitman's discovery of REM sleep was published Sept 4, 1953 (Aserinsky E, Kleitman N. Regularly Occurring Periods of Eye Motility, and Concomitant Phenomena, during Sleep. Science, 118:3062; 273-274). Surprisingly, no other sleep laboratory findings were published until 1959.

Polysomnography is a comprehensive recording of the biophysiological changes that occur during sleep. The polysomnogram, or PSG, is usually performed at night, when most people sleep; some labs can accommodate shift workers and people with circadian rhythm sleep disorders and do the test at other times of day. Polysomnogram (PSG is a multi-channel ("poly" recording ("gram" during sleep ("somno" resulting from a sleep test Polysomnography. Circadian rhythm sleep disorders are a family of Sleep disorders affecting among other things the timing of sleep The PSG monitors many body functions including brain (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG), heart rhythm (ECG), and breathing function or respiratory effort during sleep. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Electromyography (EMG is a technique for evaluating and recording the activation signal of muscles The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic

For a polysomnogram, the EEG will generally consist of four "exploring" electrodes and two "reference" electrodes (unless a seizure disorder is suspected, in which case more electrodes will be applied to document the appearance of seizure activity). The exploring electrodes are usually attached to the scalp near the central and occipitial portions of the brain via a paste that will conduct electrical signals originating from the neurons of the cortex. These electrodes will provide a readout of the brain activity that can be "scored" into different stages of sleep (1, 2, 3, 4, REM, and Wakefulness).

Pediatric polysomnography patient
Children's Hospital (Saint Louis), 2006

What is Measured

The EOG or electrooculogram consists of two electrodes; one that is placed slightly out from and above the outer canthus of the right eye and one that is placed slightly out and below the outer canthus of the left eye. Pediatrics (also spelled paediatrics) is the branch of Medicine that deals with the medical care of Infants Children and Adolescents A patient is any person who receives medical attention care or treatment. St Louis Children's Hospital is a pediatric hospital in St Louis Missouri, and is one of the premier children's hospitals in the United States Canthus (pl canthi, palpebral commissures) is either corner of the Eye where the upper and lower Eyelids meet These electrodes will pick up the activity of the eyes in virtue of the electropotential difference between the cornea and the retina (the cornea is positively charged relative to the retina). This essentially aids in determining when sleep occurs, as well as when REM Sleep occurs; of which rapid eye movements are characteristic.

The EMG or electromyogram typically uses four electrodes to measure muscle tension in the body as well as to monitor for an excessive amount of leg movements during sleep (which may be indicative of Periodic Limb Movement Disorder). Nocturnal myoclonus, also called Periodic Limb Movement Disorder (PLMD is a Sleep disorder where the patient moves limbs involuntarily during sleep and has symptoms Two leads are placed on the chin with one above the jaw line and one below. This, like the EOG, helps determine when sleep occurs as well as REM sleep. This is because when we fall asleep, we generally become more relaxed and so a marked decrease in muscle tension will occur. Also, we become partially paralyzed when we enter REM sleep so that we do not act out our dreams (although people that do not have this paralysis can suffer from REM Behavior Disorder). Finally, two more leads are placed on the anterior tibialis of each leg to measure leg movements.

Though a typical ECG (or EKG for Electrokardiogram) would use ten electrodes, only two or three are used for a polysomnogram. They can either be placed under the collar bone on each side of the chest, or one under the collar bone and the other six inches above the waist on either side of the body. These electrodes record the electrical activity of the heart as it contracts and expands, resulting in several indentifiable features such as the "P" wave, "QRS" complex, and "T" wave that can be analyzed for any abnormalities that might be indicative of an underlying heart pathology.

Nasal and oral airflow can be measured using pressure transducers, and/or a thermocouple. This allows the clinician/researcher to measure rate of respiration or help to diagnose sleep apnea. Sleep apnea is a sleep disorder characterized by pauses in Breathing during Sleep. Respiratory effort is also measured in concert with nasal/oral airflow by the use of belts. These belts expand and contract upon breathing effort.

Pulse Oxymetry helps determine changes in blood oxygen levels that often occur with sleep apnea and other respiratory problems. A pulse oximeter is a Medical device that indirectly measures the oxygen saturation of a patient's Blood (as opposed to measuring oxygen saturation directly through

In the 1970s, respiratory airflow and respiratory effort indicators were added along with peripheral pulse oximetry following the identification of the sleep disorder Sleep apnea. This article is about the Decade 1970-1979 For the Year 1970 see 1970. In Animal physiology, respiration is the transport of Oxygen from the outside air to the cells within tissues and the transport of Carbon dioxide A sleep disorder (somnipathy is a medical disorder of the Sleep patterns of a person or animal Sleep apnea is a sleep disorder characterized by pauses in Breathing during Sleep. Polysomnography is used to diagnose many types of sleep disorders including narcolepsy, restless legs syndrome, REM behavior disorder, parasomnias, and sleep apnea. Although it is not directly useful in diagnosing circadian rhythm sleep disorders, it often is used to rule out other sleep disorders.

Increasingly, polysomnography is being supplemented or replaced by Actigraphy in cases where longitudinal or large scale data sets need to be generated, or when PSG is not a cost-efficient option

External links

Actigraphy is a relatively Non-invasive method of monitoring human rest/activity cycles

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