Final answer:
Stage 1 sleep is the transition phase from wakefulness to sleep lasting a brief period of 1-7 minutes. Stage 2 is characterized by sleep spindles and K-complexes, and Stage 3 is deep sleep marked by delta waves.
Step-by-step explanation:
The sleep stage that is a transition from wakefulness to sleep and lasts 1-7 minutes is known as Stage 1 sleep.
This stage serves as a transitional phase where a person drifts off to sleep, experiencing a slowdown in respiration and heartbeat.
Sleep spindles and K-complexes, however, are most often associated with Stage 2 sleep and are indicative of a deeper level of sleep where the body goes into a state of deeper relaxation.
As we progress into Stage 3 sleep, often referred to as deep sleep or slow-wave sleep, brain wave patterns exhibit low frequency, high amplitude delta waves, and it becomes more difficult to awaken the individual.