What is the main characteristic of Sleep Stage 2?

Sleep Stage 2 is characterized by a state of decreased muscle activity and the presence of specific brain wave patterns on the EEG, known as sleep spindles and K-complexes. This stage generally reflects a deeper level of sleep than the initial stages, where the individual is less responsive to external stimuli and less likely to awaken easily. During this phase, the body begins to exhibit further muscle relaxation as it prepares for the deeper stages of sleep.

This stage is crucial for transitioning into deeper sleep stages, which play important roles in physical and mental restoration. The irregular EEG patterns, along with the presence of sleep spindles, distinguish Sleep Stage 2 from lighter sleep stages, where frequent awakenings are more common. Understanding these characteristics helps clarify the overall sleep architecture and the role that each stage plays in achieving restorative sleep.