Polysomnography Essay

Polysomnography is a sleep study test performed by a qualified sleep technologist in an effort to diagnose sleep disorders. Sleep is defined as a “naturally occurring state of unconsciousness, diminished activity of the skeletal muscles, and depressed metabolism from which a person can be awakened by stimulation” [AP]. A polysomnogram is a recorded study used to measure multiple physiologic variables and phases of sleep. This involves the use of certain equipment which allows the polysomnographist to measure natural body functions such as brain waves, muscle tension, air flow, oxygen saturation, breathing effort, as well as heart rate and rhythm. Electrocorticography (EEG) is a technique which records cortical electrical potentials directly from the brain, which serves to pinpoint physiologic changes in
Each is broken down into multiple stages. Non-REM sleep is referred to as stages N1, N2, and N3. A typical Non-REM cycle lasts approximately 90-120 minutes. In the first stage known as N1, a person is considered to be in the transitional phase between being alert and being drowsy. During this time, it is not uncommon to feel a sudden drifting or floating sensation. Additionally, this stage of sleep is also accompanied by sudden muscle contractions and the sensation of falling called hypnic myoclonia. The N1 stage of sleep is characterized as a very light sleep lasting only about 10-12 minutes. During this time, alpha activity will commonly appear on the EEG with eye closure [book pg 263]. Beta, vertex, and most commonly, theta waveforms may also be distinguished by electrocephalograms. Minute ventilation, heart rate, and blood pressure slowly begin to decrease in this stage on Non-REM sleep, while slow-rolling eye movements may be recorded by the electro-oculogram. In addition, muscle activity has slowed in comparison to being in a period of