Adult Respiratory Scoring Rules
Quick reference for adult PSG: apnea, hypopnea rules 1A and 1B, and respiratory effort–related arousals.
Adult rules only. Confirm sleep and signal quality before scoring. Follow the current AASM manual and facility protocol.
Apnea
≥90% reduction in airflow signal amplitude AND ≥10 seconds
Compare with the pre-event baseline. An oxygen desaturation or EEG arousal is not required.
Obstructive apnea
Respiratory effort continues throughout the period of absent or near-absent airflow.
Central apnea
Respiratory effort is absent throughout the period of absent or near-absent airflow.
Mixed apnea
Respiratory effort is absent initially, then returns during the ongoing airflow reduction.
If an event meets both apnea and hypopnea criteria, score it as an apnea.
Hypopnea — Rule 1A
AASM Recommended≥30% reduction in flow signal amplitude AND ≥10 seconds AND EITHER ≥3% oxygen desaturation OR An associated EEG arousal
The qualifying flow reduction and duration are always required. Either the oxygen drop or an associated EEG arousal can satisfy the final requirement.
A qualifying hypopnea can meet 1A with an EEG arousal even when the oxygen drop is less than 3%.
Hypopnea — Rule 1B
AASM Acceptable Alternative≥30% reduction in flow signal amplitude AND ≥10 seconds AND ≥4% oxygen desaturation
An EEG arousal may also occur, but it cannot replace the required 4% oxygen drop under rule 1B.
Arousal alone does not qualify under 1B.
Does it qualify as a hypopnea?
Assume a ≥30% flow reduction lasting ≥10 seconds, without meeting apnea criteria.
Oxygen drop 0% · EEG arousal: Yes
Rule 1A: YESRule 1B: NO
Oxygen drop 1–2% · EEG arousal: Yes
Rule 1A: YESRule 1B: NO
Oxygen drop 3% · EEG arousal: No
Rule 1A: YESRule 1B: NO
Oxygen drop 3% · EEG arousal: Yes
Rule 1A: YESRule 1B: NO
Oxygen drop ≥4% · EEG arousal: No or yes
Rule 1A: YESRule 1B: YES
Oxygen drop 0–2% · EEG arousal: No
Rule 1A: NORule 1B: NO
Oxygen drops are percentage-point changes from the pre-event baseline: 96% to 93% is a 3-point drop.
RERA
Respiratory effort–related arousal
A sequence of breaths lasting ≥10 seconds WITH Increasing respiratory effort OR Flattening of the inspiratory flow waveform LEADING TO An EEG arousal
The sequence does not meet apnea or hypopnea criteria under the scoring rule being applied.
No minimum oxygen desaturation is required.
Do not label every arousal a RERA. A qualifying respiratory pattern must precede the arousal.
Do not double-count the same event as both a hypopnea and a RERA.
RERA scoring is optional in the AASM framework; follow the laboratory’s scoring and reporting protocol.
Quick scoring checklist
Confirm sleep and usable signals.
Check airflow, effort, oxygenation, and EEG.
Check for apnea first.
Does the ≥90% airflow reduction last ≥10 seconds? If yes, classify using respiratory effort.
If apnea criteria are not met, evaluate hypopnea.
Apply the selected 1A or 1B definition consistently.
If neither applies, evaluate for RERA.
Look for ≥10 seconds of increasing effort or inspiratory flattening leading to an arousal.
If none of these definitions is met, do not force the finding into an event category.