What do "sleep spindles" indicate in EEG readings?

Sleep spindles are sudden bursts of oscillatory brain activity that occur primarily during NREM sleep, particularly in stage 2. They typically manifest as a series of rapid bursts of waves with a frequency of 12-16 Hz (depending on the individual) and are significant for maintaining sleep stability. The presence of sleep spindles is thought to play a crucial role in sleep processes, including facilitating memory consolidation and processing sensory information, as well as contributing to the overall restorative function of sleep.

In the context of EEG readings, a pattern characterized by sleep spindles is indicative of a specific state of sleep that is integrated into the sleep architecture. Their occurrence suggests that the brain is actively processing information and is in a somewhat stable state, which is vital for overall sleep quality. This makes them an important metric in understanding sleep health and diagnosing sleep disorders.