Final answer:
Delta waves are not a characteristic of normal drowsiness stage one sleep, which is mainly associated with alpha and theta waves. Delta waves are typical of deep, stage 3 NREM sleep.
Step-by-step explanation:
The EEG signs of normal drowsiness stage one sleep does not include delta waves. Stage one sleep is characterized by a combination of alpha and theta waves. Alpha waves are observed in the early part of this stage and are associated with a relaxed wakefulness. These waves have a frequency of 8-12 Hz and are relatively higher in amplitude and more synchronized compared to beta waves. As a person continues through stage one sleep, theta waves increase, which are even lower in frequency (4-7 Hz) and higher in amplitude.
On the other hand, beta waves are characteristic of an awake, alert state and have a higher frequency (13-30 Hz) but a lower amplitude. Delta waves, which do not occur in stage one but are prominent in deep stage 3 NREM sleep, have the lowest frequency (less than 3 Hz) and the highest amplitude.