Is Cheyne Stokes breathing (Cheyne-Stokes respiration) normal during sleep if it occurs at a low percentage of total sleep time?

Cheyne-Stokes Breathing at Low Percentages During Sleep is NOT Normal

Cheyne-Stokes breathing (CSB) is never considered "normal" during sleep, regardless of the percentage of time it occurs—even brief episodes warrant clinical attention and investigation for underlying cardiac or neurological disease. 1, 2

Why CSB is Always Pathological

The American Academy of Sleep Medicine establishes clear diagnostic thresholds that define CSB as a pathological entity requiring formal documentation and reporting, not as a normal variant:

• Diagnostic criteria require only ≥5 central apneas/hypopneas per hour over a minimum 2-hour monitoring period to meet the definition of clinically significant CSB 1
• This threshold was deliberately chosen as the minimum amount needed to identify pathology, not to distinguish normal from abnormal 1
• The guidelines explicitly state that CSB "may reflect unrecognized congestive heart failure and is a risk factor for early mortality" 1, 2

The Critical Distinction: Percentage Thresholds Are for Research, Not Normality

A common pitfall is confusing research definitions with clinical normality:

• Some studies have used >10% of recording time as a threshold to define "presence" of CSB for research purposes 1
• This 10% cutoff was used to standardize patient populations for prognostic studies, not to define what is clinically insignificant 1
• Even CSB occupying <10% of sleep time meets AASM diagnostic criteria if the AHI threshold is met 1

Prognostic Significance at Any Duration

The evidence demonstrates that CSB carries adverse prognostic implications regardless of duration:

• In heart failure patients, a central AHI >30/hour predicts poor survival, but lower levels of CSB are still associated with increased mortality 1, 2
• Longer CSB duration correlates with higher mortality and elevated NT-proBNP (a marker of cardiac dysfunction), but this represents a dose-response relationship, not a threshold for abnormality 1, 2
• Daytime CSB occurring in ≥10% of waking hours is an independent predictor of mortality (hazard ratio 3.8), but any daytime CSB is abnormal 3

Clinical Implications

When CSB is detected at any percentage during sleep:

• The AASM mandates that CSB duration (absolute or percentage of total sleep time) must be reported in sleep study reports 1
• This reporting requirement exists because CSB at any level signals potential underlying pathology requiring evaluation 1, 2
• The primary clinical response should be optimizing guideline-based heart failure therapy, as CSB most commonly reflects cardiac dysfunction 2
• Investigate for congestive heart failure, neurological disorders, atrial fibrillation, pulmonary hypertension, and renal failure 2

The Physiological Reality

CSB represents fundamental instability in respiratory control:

• The crescendo-decrescendo pattern reflects pathological oscillations in blood oxygen and carbon dioxide levels 4
• Cycle lengths of 40-90 seconds (required for diagnosis) are inherently abnormal and correlate with severity of left ventricular dysfunction 1, 2
• The pattern causes sleep disruption, arousals, hypoxemia-reoxygenation cycles, and harmful cardiovascular effects 4, 5

Bottom line: Any amount of CSB meeting diagnostic criteria (≥5 events/hour over 2 hours) is pathological and requires investigation for underlying disease, particularly heart failure. 1, 2 The notion that low percentages are "normal" is a misinterpretation of research thresholds used for patient stratification, not clinical significance.