Final answer:
Without a specific graph or table depicting the amplitudes of various brainwaves during different stages of sleep, we cannot determine the highest EEG amplitude point. Typically, higher amplitude waves occur during deep sleep stages.
Step-by-step explanation:
To determine when the general amplitude of the EEG was highest, we refer to the brainwave activity and look for the stage with the greatest wave heights, as amplitude refers to the height of the waves. According to the key terms provided, alpha waves, which are prevalent during the early part of NREM stage 1 sleep, have fairly low amplitude, whereas beta waves characteristic during wakefulness have a very low amplitude. Given this information, neither alpha waves nor beta waves would represent the highest amplitude. Unfortunately, without a specific graph or additional context about other brainwave types and their respective amplitudes during different sleep stages, we cannot conclusively determine when the EEG's amplitude was the highest. Researchers might expect higher amplitude waves during deep sleep stages, like delta waves found in stage 3 (NREM) sleep, which would not be represented by the frequency ranges of alpha or beta waves.