Which of the following is NOT a sign of normal drowsiness in NREM Stage N1 sleep?

In NREM Stage N1 sleep, the brain’s electrical activity is characterized by several specific patterns that indicate a transition from wakefulness to deeper stages of sleep. Increased theta activity, greater beta activity, and alpha activity moving anteriorly are all considered signs of normal drowsiness during this stage of sleep.

Increased theta activity is commonly observed as a hallmark of NREM sleep, especially in the transition from wakefulness. Greater beta activity is also indicative of an active, alert state that can still be present during the onset of sleep. Alpha activity, which is associated with relaxed wakefulness, moving anteriorly can be seen as the brain transitions into early sleep.

However, left anterior delta activity is not typical for NREM Stage N1. Delta waves are most commonly associated with deeper stages of NREM sleep (stages N2 and N3) rather than the very light sleep of N1. Thus, the presence of left anterior delta activity would not fit within the expected characteristics of normal drowsiness in NREM Stage N1, making it the option that does not conform with typical EEG findings for this sleep stage.