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A hypnogram is a form of polysomnography; it is a graph that represents the stages of sleep as a function of time. It was developed as an easy way to present the recordings of the brain wave activity from an electroencephalogram (EEG) during a period of sleep. It allows the different stages of sleep: rapid eye movement sleep (REM) and non-rapid ...
Sample hypnogram showing one sleep cycle (the first of the night) from NREM through REM. The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and ...
Hypnogram showing sleep architecture from midnight to 6:30 am, with deep sleep early on. There is more REM (marked red) before waking. (Current hypnograms reflect the recent decision to combine NREM stages 3 and 4 into a single stage 3.) Understanding the activity of different parts of the brain during sleep can give a clue to the functions of ...
Polysomnography (PSG) is a multi-parameter type of sleep study [1] and a diagnostic tool in sleep medicine.The test result is called a polysomnogram, also abbreviated PSG.The name is derived from Greek and Latin roots: the Greek πολύς (polus for "many, much", indicating many channels), the Latin somnus ("sleep"), and the Greek γράφειν (graphein, "to write").
Sleep. Sleeping Girl, Domenico Fetti, c. 1615. Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environment.
Peripheral Arterial Tone ( PAT) is a noninvasive measure designed to track pulsatile volume changes in peripheral arterial beds. The collected information gives specialists important insight into the autonomic nervous system and the cardiovascular system. PAT technology is mostly used to detect heart disease, erectile dysfunction and ...
Rapid eye movement sleep. Rapid eye movement sleep ( REM sleep or REMS) is a unique phase of sleep in mammals (including humans) and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly. The REM phase is also known as paradoxical sleep ...
Brian Atwater, a U.S. Geological Survey scientist emeritus, shows off tsunami-deposited mud. COPALIS BEACH, WASH. — When Japan issued its first-ever “megaquake” warning last week, Harold ...