Which of the following can occur during Stage REM EXCEPT?

In Stage REM (Rapid Eye Movement) sleep, specific EEG patterns and phenomena are typically observed. The correct answer indicates the exception to what typically occurs during this stage.

Stage REM is characterized by sawtooth waves, which are sharp waveforms that reflect the brain's activity during this phase. Transient muscle activity is also common, as the body may exhibit small bursts of movement despite being in a state of atonia (muscle paralysis) that prevents larger movements. Sleep spindles, brief bursts of brain activity, are primarily associated with Stage NREM sleep instead of REM, which makes their appearance less relevant when discussing typical REM characteristics.

The presence of 0.5 Hz - 2 Hz wave activity is not typical of Stage REM. In this stage, brain activity tends to display a mix of low-frequency waves interspersed with bursts of rapid activity. While some low-frequency activity can exist, the specific range of 0.5 Hz to 2 Hz is more indicative of deeper NREM sleep stages rather than the predominantly mixed frequency activity characteristic of REM sleep. Thus, acknowledging the features typically associated with REM sleep clarifies why transient muscle activity, sawtooth waves, and potentially the presence of sleep spindles would not be considered