| S1-S4 | Sleep Stages 1-4 |
| SA | Sleep apnea |
| SAD | Seasonal Affective Disorder |
| SAHS | Sleep apnea/hypopnoea syndrome |
| SaO2 | % of normal Oxygen level in the blood. |
| SaO2 | Blood oxygen saturation |
| SAS | Sleep Apnea Syndrome |
| SCOLIOSIS | A twisting of the spine that can limit lung expansion and lead to problems of underbreathing which can be alleviated by overnight breathing support. |
| SDB | Sleep disordered breathing |
| Sedatives | Compounds tending to calm and reduce nervousness or excitement and foster sleep. |
| Sedentary Situation | Not requiring physical activity e.g. working at a desk sitting in a meeting or in a theater watching television. |
| SEGS | Number of REM Segments |
| SEI | Sleep efficiency index |
| SEM | Slow Eye Movement |
| Septoplasty | Surgery on the nasal septum (dividing the nasal passage). |
| Serotonin | Neurotransmitter in the brain that modulates mood appetite sexual activity aggression body temperature and sleep. |
| Shiftwork | Working hours outside of the conventional daytime hours of 9:00 a.m. to 5:00 p.m. |
| SIDS | Sudden Infant Death Syndrom |
| SILASTIC RING GASTROPLASTY | An operation to limit eating (the last resort!) not very pleasant. If you overeat you are sick. |
| SL | Sleep latency |
| Sleep | A state marked by lessened consciousness lessened movement of the skeletal muscles and slowed-down metabolism. |
| Sleep Apnea | Cessation of breathing for 10 or more seconds during sleep. |
| Sleep architecture | NREM/REM stage and cycle infrastructure of sleep understood from the vantage point of the quantitative relationship of these components to each other. |
| Sleep architecture | A term that refers to all aspects of your sleep pattern including total sleep time sleep latency sleep efficiency and sleep stages. |
| Sleep center | A sleep disorders center. Provides testing and treatments for all sleep disorders. A sleep center can earn accreditation from the AASM. |
| Sleep cycle | Synonymous with NREM-REM cycle. |
| Sleep cycle | A transition through all four sleep stages. Each complete cycle lasts about 90 to 110 minutes. Most adults will go through four to six cycles in a full night of sleep. Children have much shorter sleep cycles than adults. The sleep cycle of a one-year-old may last about 45 minutes. Once a child nears 10 years of age the length of his or her sleep cycle is similar to that of an adult. |
| Sleep Debt | Result of recurrent sleep deprivation which occurs over time when an individual does not experience a sufficient amount of the restorative daily sleep that is required to maintain a sense of feeling rested and refreshed. |
| Sleep Deprivation | Acute or chronic lack of sufficient sleep. |
| Sleep Disorders | Broad range of illnesses arising from many causes including dysfunctional sleep mechanisms abnormalities in physiological functions during sleep abnormalities of the biological clock and sleep disturbances that are induced by factors extrinsic to the sleep process |
| Sleep efficiency | The percentage of total recording time that you spend asleep. |
| Sleep efficiency (SE) | Proportion of sleep in the period potentially filled by sleep--ratio of total sleep time to time in bed. |
| Sleep Episode | Interval of sleep that may be voluntary or involuntary. |
| Sleep Extension | Extending sleep time by increasing the time in bed. |
| Sleep Fragmentation | Brief arousals occurring throughout the night reducing the total amount of time spent in the deeper levels of sleep. |
| Sleep hygiene | Conditions and practices that promote continuous and effective sleep including regularity of bedtime and arise time; conforming time spent in bed to the time necessary for sustained and individually adequate sleep (i.e. the total sleep time sufficient to avoid sleepiness when awake); restriction of alcohol and caffeine beverages in the period prior to bedtime; employment of exercise nutrition and environmental factors so that they enhance not disturb restful sleep. |
| Sleep Hyperhydrosis | Excessive sweating during sleep. |
| Sleep Inertia | Feelings of grogginess and/or sleepiness that persist longer than 10 to 20 minutes after waking up. |
| Sleep interruption | Breaks in the sleep architecture resulting in arousal and wakefulness. |
| Sleep lab | A laboratory for sleep related breathing disorders. Provides testing for all sleep disorders and treatments for sleep-related breathing disorders such as obstructive sleep apnea and snoring. A sleep lab can earn accreditation from the AASM. |
| Sleep latency | Time period measured from "lights out " or bedtime to the beginning of sleep. |
| Sleep latency | The length of time from when the lights are turned out to sleep onset. |
| Sleep log (diary) | Daily written record of an individual's sleep-wake pattern containing such information as time of retiring and arising time in bed estimated total sleep period number and duration of sleep interruptions quality of sleep daytime naps use of medications or caffeine beverages nature of waking activities and other data |
| Sleep Mentation | Thoughts feelings images perceptions hallucinations and active dreams taking place during sleep. |
| Sleep onset | Transition from wake to sleep normally into NREM stage 1 (but in certain conditions such as infancy and narcolepsy into stage REMS). |
| Sleep onset | The moment when you fall asleep. |
| Sleep Onset Imagery | Images and experiences during the moments following the transition from wake to sleep. |
| Sleep paralysis | Waking and not being able to move for a short period of time usually occurs out of REM (dream) sleep. |
| Sleep pattern | (24 hour sleep-wake pattern) individual's clock hour schedule of bedtimes and rise times as well as nap behavior: may also include time and duration of sleep interruptions. |
| Sleep Related Accidents | Accidents caused by individuals who were sleep deprived and who as a result had impaired judgment. |
| Sleep Restriction | Limitation of the number of hours in bed. |
| Sleep specialist | A licensed doctor who is board certified in the subspecialty of sleep medicine. He or she specializes in assessing testing diagnosing managing and preventing sleep disorders. |
| Sleep spindle | Episodically appearing spindle-shaped aggregate of 12-14 Hz waves with a duration of 0.5-1.5 seconds one of the identifying EEG phenomena of NREM stage 2 sleep. |
| Sleep stage 1 | A stage of NREM sleep occurring after wake. Its criteria consist of a low-voltage EEG with slowing to theta frequencies alpha activity less than 50% EEG vertex spikes and slow rolling eye movements; no sleep spindles K-complexes or REMS. Stage 1 normally assumes 4-5% of total sleep. |
| Sleep stage 2 | A stage of NREM sleep characterized by sleep spindles and K complexes against a relatively low-voltage mixed-frequency EEG background; high-voltage delta waves may comprise up to 20% of stage 2 epochs; usually accounts for 45-55% of total sleep time. |
| Sleep stage 3 | A stage of NREM sleep defined by at least 20 and not more than 50% of the period (30 second epoch) consisting of EEG waves less than 2 Hz and more than 75 uV (high -amplitude delta waves); a "delta" sleep stage; with stage 4 it constitutes "deep "NREM sleep; appears usually only in the first third of the sleep period; usually comprises 4-6% of total sleep time. |
| Sleep stage 4 | All statements concerning NREM stage 3 apply to stage 4 except that high-voltage slow EEG waves cover 50% or more of the record; NREM stage 4 usually takes up 12-15% of total sleep time. Somnambulism sleep terror and sleep-related enuresis episodes generally start in stage 4 or during arousals from this stage. |
| Sleep Stage Demarcation | Significant polysomnographic characteristics that distinguish the boundaries of the sleep stages. |
| Sleep stage NREM | Major sleep state apart from REMS; comprises sleep stages 1-4. |
| Sleep stage REM | The stage of sleep found in all mammal studies including man in which brain activity is extensive brain metabolism is increased and vivid hallucinatory imagery or dreaming occurs (in humans). Also called "paradoxical sleep" because in the face of this intense excitation of the CNS and presence of spontaneous rapid eye movements resting muscle activity is suppressed.The EEG is a low-voltage fast-frequency non alpha record. Stage REMS is usually 20-25% of total sleep time. |
| SLEEP STAGES | Sleep is conventionally divided into five stages. Four of these are called non-REM sleep the other is REM (or Rapid Eye Movement) sleep. REM sleep is when we dream and the brain is virtually awake. Non_REM sleep is graded 1 to 4 and represents increasing depths of sleep. This is the sleep required to refresh with the two deeper stages 3 and 4 called slow wave sleep. |
| Sleep stages | The four unique periods that make up one sleep cycle. The nature of your sleep is different in each stage. A typical sleep cycle consists of three stages of N sleep (N1 N2 and N3) followed by R sleep. |
| Sleep structure | Similar to sleep architecture. Sleep structure in addition to encompassing sleep stage and cycle relationships assesses the within-stage qualities of the EEG and other physiological attributes. |
| Sleep talking | Talking in sleep takes place during stage REMS representing a motor breakthrough of dream speech or in the course of transitory arousals from NREMS and other stages. Full consciousness is not achieved and no memory of the event remains. |
| Sleep technologist | A health-care professional who assists in the evaluation and follow-up care of patients with sleep disorders. A sleep technologist works under the direct supervision of a sleep specialist. |
| Sleepiness | (somnolence drowsiness) - difficulty in maintaining the wakeful state so that the individual falls asleep if not actively kept aroused; not simply a feeling of physical tiredness or listlessness. |
| Sleeping Pills | Compounds that have a sedative effect used to produce sleepiness. |
| Sleep-maintenance DIMS or insomnia | Disturbance in maintaining sleep once achieved; persistently interrupted sleep without difficulty falling asleep. |
| Sleep-onset REM period | A typical beginning of sleep by entrance directly into stage REM. |
| Sleep-wake shift | (change -reversal) sleep wholly or partially moved to a time of customary waking activity and the latter is moved to the habitual sleep period; common in jet lag and shift work. |
| Sleep-Wake Transition Disorder | Disorder occuring during the transition from wakefulness to sleep or from one sleep stage to another; a form of parasomnia. |
| Sleep-wake, 24 hour cycle | The clock hour relationships of the major sleep and wake phases in the 24 hour cycle: similar to sleep pattern. |
| Sleepwalker or Sleepwalking | Individual subject to somnambulism (one who walks while sleeping). Sleepwalking typically occurs in the first third of the night during deep NREM sleep (stages 3 and 4). |
| SLOW WAVE SLEEP | See sleep stages. |
| Slow wave sleep (SWS) | Sleep stage 3 - a stage of NREM sleep defined by at least 20 and not more than 50% of the period (30 second epoch) consisting of EEG waves less than 2 Hz and more than 75 uV (high -amplitude delta waves); a "delta" sleep stage; with stage 4 it constitutes "deep "NREM sleep; appears usually only in the first third of the sleep period; usually comprises 4-6% of total sleep time.
Sleep stage 4 - all statements concerning NREM stage 3 apply to stage 4 except that high-voltage slow EEG waves cover 50% or more of the record; NREM stage 4 usually takes up 12-15% of total sleep time. Somnambulism sleep terror and sleep-related enuresis episodes generally start in stage 4 or during arousals from this stage. |
| SmartPAP (Smart CPAP) | (Smart [Continuous] Positive Airway Pressure) Medical device used in the treatment of obstructive sleep apnea providing preset levels of continuous airflow and automatically adjusting to keep the breathing passages open by sensing changes in airway integrity. The air flows from the device through a tube that connects to a nose or face mask. |
| Snoring | Noise produced primarily with inspiratory respiration during sleep owing to vibration of the soft palate and the pillars of the oropharyngeal inlet. Many snorers have incomplete obstruction of the upper airway and may develop obstructive sleep apnea. |
| Snoring | The vibration of tissue in the back of your throat as you breathe making a noise during sleep. Frequent loud snoring is a warning sign for obstructive sleep apnea. |
| SNORING AROUSALS | Sleep can be disturbed not only by actual episodes of stopping breathing but also by snoring alone (when a big increase in breathing effort is required to overcome the narrowing of the upper airway that led to the snoring). |
| SO | Sleep onset |
| Soft Palate | Membranous and muscular fold suspended from the posterior margin of the hard palate and partially separating the oral cavity from the pharynx. |
| Softcap | Type of headgear. |
| Somatic Complaints | Awareness of pain or problems in the body. |
| Somnambulism | Walking while asleep. |
| Somnifacient | Inducing sleep; hypnotic as in a drug. |
| Somnolence | prolonged drowsiness or sleepiness. |
| Somnoplasty | Commercial name for radiofrequency treatment of certain sleep disorders. |
| Soporific | Causing or tending to cause sleep. |
| SOPWN | Spouse of a PWN |
| SOREM | Sleep onset REM |
| SP | Sleep Paralysis |
| Spindle REMS | Condition in which sleep spindles persist atypically in REMS; seen in chronic DIMS conditions. |
| Split-night study | Doing an overnight sleep study and a CPAP study in the same night. During an overnight sleep study. A CPAP study may be performed right away if you show signs of having severe OSA. |
| SPT | Sleep Period Time |
| Squib | Use of sensitive superconductor Josephson junction detectors to map brain activity |
| SRBD | Sleep-related breathing disorder |
| SRRD | Sleep-related respiratory disturbance |
| SSDB | Social Security Disability Benefits |
| SSI | Supplemental Security Income |
| SSRI | Selective Serotonin Reuptake Inhibitor (the family of anti-depressants that include Prozac Zoloft and Wellbutrin among others). |
| SSS | Stanford Sleepiness Scale |
| Stanford Sleepiness Scale (SSS) | 7-point rating scale consisting of seven numbered statements describing subjective levels of sleepiness/alertness. |
| STD | Short Term Disability *OR* Sexually Transmitted Disease |
| STRYCHNINE | Has been tried to cure sleep apnoea! Works a bit but there are worries that spouses might be tempted to give an overdose at 3 am when the snoring is particularly bad! |
| Subjective Sleepiness | Feelings of sleepiness. |
| Substance Abuse | Excessive use of alcohol or drug; substances can cause sleep disturbances. |
| Subwakefulness syndrome | Syndrome defined as a defect in the CNS support system for waking. The few individuals reported with subwakefulness syndrome have daytime drowsiness and daytime sleep episodes that are always composed of NREMS stages 1 or 2. The naps occur repetitively. |
| Sudden Infant Death Syndrome (SIDS) | Sudden and unexpected death of an apparently healthy infant whose death remains unexplained after the performance of an adequate postmortem investigation. Death usually occurs during sleep. SIDS is a classification that is used to describe a deceased infant. It is not a disease nor can it be a diagnosis for a living baby. |
| SWDS | Sleep-wake schedule disorder |
| SWL | Slow wave latency |
| SWS | Slow wave sleep |
| Synchronization | Chronobiological term used to indicate that two or more rhythms recur with the same phase relationship. In an EEG tracing the term is used to indicate an increased amplitude with an occasional decreased frequency of the dominant activities. |
| Synchrony | Scheduling sleep to synchronize with the biological clock. |
| Sz | Schizophrenia |
