Table 1.
Commonly used terminologies in sleep medicine
| Acronym | Term | Description |
|---|---|---|
| SE | Sleep Efficiency (%) | The proportion of time spent sleeping through the night |
| NREM | NREM sleep | The initial stages of sleep (N1 + N2 + SWS); about 80% of sleep |
| N1 | Stage 1 sleep | Characterized by low eye movements, waves with low amplitude and, mostly 4-7 Hz frequency |
| N2 | Stage 2 sleep | The sleep stage that demonstrates sleep spindles and K complexes |
| N3/SWS | Slow Wave Sleep (stages 3 + 4) | The presence of high amplitude and low frequency (0.5-2Hz), ≥ 20% of the epoch |
| REM | Rapid Eye Movement sleep | Sleep with saw tooth waveforms, rapid eye movements and low muscle tone |
| SOL | Sleep Onset Latency (min) | Time from “lights out” until the onset of sleep in the reading pane |
| REM-L | REM Onset Latency (min) | Interval of time from onset of sleep to the appearance of the first epoch of REM sleep |
| S1 | Stage 1 (%) | The fraction of sleep that is spent in N1 (total Stage 1 sleep/TST × 100); usually about 4-5% |
| S2 | Stage 2 (%) | The fraction of sleep that is spent in N2 (total Stage 2 sleep/TST × 100); usually about 45-55% |
| SWS | Slow Wave Sleep (%) | The percentage of sleep that is spent in SWS (total SWS sleep/TST × 100); usually about 16-21% |
| REM | REM (%) | The percentage of sleep that is spent in REM (total REM sleep/TST × 100); usually about 20-25% |
| Apnea | (polysomnography or home sleep test) | A complete cessation of airflow for ≥ 10 seconds |
| Hypopnea | (polysomnography or home sleep test) | A partial cessation of airflow for ≥ 10 seconds, and, either a ≥ 4% drop in SpO2, or, an arousal (as seen on electroencephalogram) |
| AHI | Apnea Hypopnea Index (events/Hour) | Total number of apneas and hypopneas per hour of sleep, i.e. total number of apneas and hypopneas/TST |
| Advance | Phase Advance | Shift of the sleep cycle to an earlier time during a circadian period (24 hours) |
| Delay | Phase Delay | Shift of the sleep cycle to a later time during a circadian period (24 hours) |
| SRBD | Sleep Related Breathing Disorder | Abnormalities of respiration during sleep; include OSA, CSA, obesity hypoventilation and hypoventilation syndromes |
| OSA | Obstructive Sleep Apnea | A syndrome with symptoms (loud snoring and breathing interruptions)/cardio-metabolic syndrome + AHI ≥ 5 events/hr of sleep |
| CSA | Central Sleep Apnea | A syndrome with symptoms (sleepiness, insomnia, snoring and witnessed apneas)/A.Fibrillation/CHF + ≥ 5 central events/hr of sleep |
| CPAP | Continuous Positive Airway Pressure | A machine delivering air at a continuous pressure in order to prevent collapse of the air passage during sleep |
| BiPAP | Bi-level Positive Airway Pressure | A machine delivering air at two pressures; a higher pressure during inspiration and a lower pressure during expiration |
| ASV | Adaptive Servo-Ventilation | A specialized form of positive airway pressure support where the delivered pressure changes when respiratory events are detected |
| CBT-I | Cognitive Behavioral Therapy for Insomnia | A manualized behavioral treatment for insomnia, consisting of sleep restriction, stimulus control and cognitive therapy, for ≤ 8 weeks |
Data from American Academy of Sleep Medicine (AASM). The AASM Manual for the scoring of Sleep and Associated Events, 2007; and American Academy of Sleep Medicine (AASM), 2012. Available at: http://www.sleepnet.com/definition.html. Accessed Oct 28 2017.