It is not that more sleep rhythms are better in general, but that a particular cross-regional coupling tracks whether a memory is retained. The study found that spikes coupled to sleep oscillations, particularly to the slow oscillations sitting at the top of the cascade, predicted worse overnight performance. What 19 Epilepsy Patients Can and Cannot Tell UsGeneralization is the central limitation and deserves stating plainly rather than in a closing line. Drug-resistant epilepsy alters brain networks and medications affect sleep, so generalization is an inference rather than a demonstrated fact. Spikes coupled to sleep oscillations, especially slow oscillations, predicted worse overnight memory performance.