Final answer:
Our brain waves slow down as we fall deeper into sleep, transitioning from higher-frequency beta waves during wakefulness to alpha and theta waves in the early NREM stages, and ultimately to delta waves in deep NREM sleep.
Step-by-step explanation:
As we fall deeper into sleep, our brain waves tend to slow down. This slowing down is observed as we enter NREM sleep. Initially, during stage 1 NREM sleep, the brain produces alpha waves which are lower in frequency (8-12 Hz) compared to the beta waves that dominate when we are awake. As an individual progresses into stage 1 sleep, theta wave activity increases which are even lower in frequency (4-7 Hz) and higher in amplitude. Moving into stage 2 sleep, we see the presence of theta waves, sleep spindles, and K-complexes. In the deep sleep of stage 3 NREM, characterized by slow-wave sleep, delta waves with the lowest frequency (less than 3 Hz) and highest amplitude predominate.
The REM sleep stage features rapid eye movements and a brain wave pattern that resembles wakefulness, despite the individual being in a deep sleep state and dreaming. Each stage has distinct brain wave patterns that can be measured in terms of frequency and amplitude, reflecting the dynamic nature of sleep.