Final answer:
Brainwave patterns show four different stages: beta waves while awake, transitioning to alpha waves, then to theta waves in stage 1 NREM sleep, slow-wave delta waves in stages 3 and 4 NREM sleep, and finally REM sleep which is similar to wakefulness. Each stage plays an important role in different biological and psychological functions.
Step-by-step explanation:
The different levels of alertness and states of consciousness are closely associated with brainwave patterns, which can be measured using an EEG (electroencephalogram). When we are awake, brain activity is dominated by beta waves, characterized by high frequency (13–30 Hz) and low amplitude. As we switch from wakefulness to sleep, the activity transitions first to alpha waves, then with progressive deepening of sleep to theta waves, and eventually to delta waves in the deepest stages of non-REM (NREM) sleep.
During stage 1 NREM sleep, our brainwaves exhibit alpha and theta waves which indicate a transitional phase between wakefulness and sleep. It is easy to wake someone up at this stage. As we move into stage 2 NREM sleep, the presence of sleep spindles and K-complexes become prominent. In stages 3 and 4 of NREM sleep, often grouped together as slow-wave sleep, delta waves dominate, indicating the deepest sleep. Finally, REM sleep mimics brainwave patterns of wakefulness, characterized by rapid eye movement and where most dreaming occurs.
Each stage of sleep serves different biological functions, with the deepest stages involved in physical growth and memory consolidation, and REM sleep associated with learning and mental rejuvenation.