Cheyne–Stokes respiration

Cheyne–Stokes respiration is a rhythmic waxing and waning of breathing: breaths grow gradually deeper, peak, then fade away to a pause with no breathing at all, before the cycle repeats. It looks like a tide rolling in and out.

It arises from an unstable control loop. The feedback between carbon dioxide levels and the brain's response becomes delayed or overly sensitive, so the system overshoots and undershoots instead of settling. When carbon dioxide rises the person breathes too hard and drives it too low, which then triggers a pause until carbon dioxide climbs again, producing the characteristic crescendo-decrescendo cycle ending in apnea.

It is commonly seen in heart failure, after a stroke, and in some people at high altitude or during sleep, and it can occur in the dying. While a few cycles in sleep can be benign, persistent Cheyne–Stokes breathing usually signals an underlying heart or brain problem, and management focuses on treating that cause.