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Sawtooth Waves A form of theta rhythm (4-7 Hz) that occurs during REM sleep and is characterized by a notched waveform
Seasonal Affective Disorder (SAD) A seasonal disruption of mood that occurs during the winter months and ceases with the advent of spring; Symptoms usually begin in September when days begin to shorten, and last through the winter and into March when the days begin to lengthen again; Light therapy plays a big part in its origin and treatment
Sensitivity A measure of the amount of negative pressure that must be generated by a patient in order to trigger a mechanical ventilator into the inspiratory phase
Sinusitis An irritation or inflammation of the lining of the sinuses; When the mucous membranes lining the sinus walls become inflamed, these openings become blocked and the sinuses do not drain properly
Sleep Architecture The NREMS/REMS stage and cycle infrastructure of sleep understood from the vantage point of the quantitative relationship of these components to each other
Sleep Cycle Synonymous with the non-REM-REM sleep cycle
Sleep Efficiency or Sleep Efficiency Index The proportion of sleep in the period potentially filled by sleep, that is, the ratio of total sleep time to time in bed
Sleep Hygiene The conditions and practices that promote continuous and effective sleep; Including: Regularity of bedtime and arise time, i.e., Going to bed and getting up at the same time each day; Spend only enough time in bed to get an adequate amount of sleep, usually 8-9 hours for normal adults; Restriction of alcohol and caffeinated beverages in the period prior to bedtime; Proper exercise, nutrition, and control of environmental factors, such as noise, light and temperature so that they enhance, and not disturb, restful sleep
Sleep Latency The period of time measured from lights out, or bedtime, to the onset of sleep
Sleep Log A daily, written record of a person’s sleep-wake pattern, containing information such as time of retiring and arising, time in bed, etc.
Sleep Onset The transition from waking to sleep, normally into non-REM
Sleep Paralysis Immobility of the body that occurs in the transition from sleep to wakefulness; A partial manifestation of REM sleep
Sleep Spindle Spindle-shaped bursts waves which are one of the identifying features of Sleep stage II
Sleep Stage I Relatively low-voltage, mixed-frequency EEG without rapid eye movements; Slow eye movements are often present; Vertex sharp waves may be seen; EMG activity is not suppressed
Sleep Stage II 12-14 cps sleep spindles and K complexes on a background of relatively low-voltage, mixed-frequency EEG activity
Sleep Stage III Moderate amounts (20-50%) of high-amplitude (75 uV or greater) slow-wave (2 cps or slower) EEG activity
Sleep Stage IV Predominance (greater that 50%) of high- amplitude (75 uV or greater) slow-wave (2 cps or slower) EEG activity
Sleep-onset REM Period The beginning of sleep by entrance directly into stage REM sleep; The onset of REM occurs within 10 minutes of sleep onset
Slow-wave Sleep Sleep characterized by EEG waves of duration slower than 4 Hz; Synonymous with Sleep stages III and IV combined (Delta sleep)
Spacer A small device that attaches to a metered dose inhaler medication in order to help improve the delivery of drugs to the lungs and reduce unwanted side effects such as the unpleasant taste of some drugs
Static Compliance A measure of the distensibility of the lung (i.e., the pressure required to maintain a given volume of inflation)
Sudden Infant Death Syndrome (SIDS) The sudden and unexplained death of an infant who has no known illness, usually under one year of age, that remains unexplained after the performance of a complete postmortem investigation, including an autopsy, an examination of the scene of death and review of the case history
Synchronous Intermittent Mandatory Ventilation (SIMV) Periodic assisted ventilation with positive pressure, with the patient breathing spontaneously between breaths
Adult Respiratory Distress Syndrome (ARDS) Indicates respiratory failure with life threatening distress and hypoxemia, associated with acute pulmonary injuries

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