What is a defining feature of Stage N2 (Stage 2) sleep?

Stage N2 sleep, also known as Stage 2 sleep, is characterized by specific brain wave patterns that are critical for understanding the sleep cycle. One of the defining features of this stage is the presence of sleep spindles, which are bursts of oscillatory brain activity that occur within a frequency range of 12-16 Hz. Sleep spindles are thought to play a role in memory consolidation and are a reliable indicator of Stage 2 sleep in an EEG recording.

Additionally, Stage N2 sleep typically involves the absence of rapid eye movements, which are hallmarks of REM sleep, and is not primarily identified by delta waves, which are more prominent in deep sleep stages (Stage N3). While POSTs (positive occipital sharp transients) can also be observed in the sleep EEG, they are not specific to Stage N2 and can occur in other contexts.

Understanding these characteristics helps to differentiate Stage N2 from other stages of sleep during an EEG assessment, highlighting its unique signature in the overall sleep architecture.