Table 1.
Representative sleep parameters derived by laboratory polysomnography
| Type | Parameter | Abbreviation | Derivation |
|---|---|---|---|
| Sleep scoring data | Total recording time | TRT | Time from “light out” to “light on”, in min |
| Total sleep time | TST | Time spent in N1 + N2 + N3 + R, in min | |
| Sleep latency | SL | Time from “light out” to 1st epoch of any sleep, in min | |
| REM sleep latency | RL | Time from sleep onset to 1st epoch of stage R, in min | |
| Wake after sleep onset | WASO | TRT-SL-TST, in min | |
| Sleep efficiency | SE | (TST/TRT) × 100 | |
| Time in each stage | N1, N2, N3, R | Time in each of N1, N2, N3, and R stages, in min | |
| Percent in each stage | N1%, N2%, N3%, R% | (Time in each stage/TST) × 100 | |
| Movement events | Number of periodic limb movements of sleep | PLMS | Number of limb movements during TST |
| PLMS index | PLMSI | (PLMS/TST) × 60, number of movements per hour | |
| Respiratory events | Number of obstructive sleep apneas | #OSA | Number of obstructive apneas during TST |
| Number of central sleep apneas | #CSA | Number of central apneas during TST | |
| Number of mixed sleep apneas | #MSA | Number of mixed apneas during TST | |
| Number of hypopneas | #SH | Number of hypopneas during TST | |
| Number of sleep apneas | #SA | #OSA + #CSA + #MSA | |
| Apnea index | AI | (#SA/TST) × 60, number of apneas per hour | |
| Hypopnea index | HI | (#SH/TST) × 60, number of hypopneas per hour | |
| Apnea–hypopnea index | AHI | ((#SA + #SH)/TST) × 60, number of apneas and hypopneas per hour | |
| Number of oxygen desaturations | #OD | Number of oxygen desaturations ≥ 3% or 4% during TST | |
| Oxygen desaturation index | ODI | (#OD/TST) × 60, number of oxygen desaturations per hour |