Final answer:
The stage of sleep that occurs as we drift off is called stage 1 sleep, a transitional phase between wakefulness and sleep marked by a change in brain wave patterns and a reduction in physical activities like respiration and heartbeat.
Step-by-step explanation:
The stage of sleep that occurs between wakefulness and sleep, the period during which we drift off to sleep, is known as stage 1 sleep. This transitional phase is characterized by a decrease in brain wave frequency and an increase in amplitude.
As we transition from being awake with high levels of sensory awareness and thought, to stage 1 sleep, our respiration and heartbeat rates slow down, and we experience a marked change in brain wave patterns from alpha waves to theta waves. The brain wave activity changes can be visualized using an EEG, which shows us entering a different state of consciousness.
Stage 1 sleep is part of the NREM (non-REM) stages of sleep, which are followed later by REM sleep. Each stage of NREM and REM sleep can be distinguished by specific patterns of brain waves, which reflect our level of consciousness and restfulness. These sleep stages and the transitions between them are vital for physical growth, learning, and memory.