Acute encephalopathy is a rapidly developing brain disorder that is often seen in critically ill patients in the intensive care unit (ICU). This diagnosis can have multiple causes, of which sepsis is one of them. Sepsis-associated encephalopathy (SAE) indicates compromised brain function due to the accumulation of metabolic by-products or the cause of the sepsis itself. One distinctive electroencephalography (EEG) feature is the presence of polymorphic delta (PMD) waves, which can be present even before the patient has the clinical manifestations of sepsis. These PMD waves can be detected using a single-channel EEG device. In this case report, we present a patient who exhibited no overt clinical signs of sepsis or delirium, yet presented PMD waves and EEG slowing. This patient experienced two episodes of sepsis during hospitalization. This article serves as a case report to illustrate that sepsis may be detectable 'early' on a single-channel EEG due to the presence of distinct features like PMD waves.