Final answer:
Sleep cycles consist of multiple stages, including REM and multiple NREM stages. Sleep spindles and K-complexes are characteristic of stage 2 NREM sleep, while deep sleep in stage 3 NREM involves delta waves. Sleep stages are important to sleep quality and cognitive functions like learning and memory.
Step-by-step explanation:
The correct statement regarding progressive cycles during sleep is c) Sleep stages alternate in a predictable sequence throughout the night. Sleep is an intricate state composed of multiple stages, which are categorized into REM (Rapid Eye Movement) sleep and NREM (Non-REM) sleep stages. Looking at the specific stages of NREM, sleep spindles and K-complexes are most commonly associated with stage 2 of NREM sleep.
During stage 2 sleep, the brain's activity is marked by theta waves that are interrupted by bursts of rapid activity known as sleep spindles, which can be important for learning and memory. In addition, K-complexes occur during this stage, which are large, high amplitude patterns of brain activity that may serve as responses to environmental stimuli while sleeping. Progressing further into the sleep cycle, stage 3, also known as deep sleep or slow-wave sleep, is characterized by low frequency, high amplitude delta waves.
Both NREM and REM sleep play crucial roles in various cognitive functions, including learning and memory, and therefore, sleep stages do influence overall sleep quality. REM sleep, which features dreaming and a near-paralysis of voluntary muscles, also presents brain wave patterns that are quite similar to wakefulness.