What does the presence of sleep spindles indicate?

Sleep spindles are characterized by their specific appearance on an EEG as bursts of oscillatory brain activity and are most notably present during Stage N2 sleep. This stage is a light sleep phase that serves as a transition from wakefulness to deeper sleep stages. The presence of sleep spindles in N2 is significant because they are associated with the brain's processes of memory consolidation and sensory processing. During this stage, not only are sleep spindles evident, but the brain is also actively engaged in inhibiting outside stimuli, allowing for a more restful sleep. In contrast, the other stages of sleep, such as N1, N3, and REM, exhibit different EEG patterns and lack the distinctive sleep spindles that mark N2 sleep.