Final answer:
The pre-hypnogogic stage of sleep, also known as stage 1 sleep, is a transitional phase between wakefulness and sleep. It is characterized by the presence of both alpha and theta brain waves. This stage usually lasts for a few minutes before transitioning into stage 2 sleep.
Step-by-step explanation:
The pre-hypnogogic stage of sleep is also referred to as stage 1 sleep. It is a transitional phase that occurs between wakefulness and sleep.
During this stage, brain wave patterns show a slowdown in frequency and an increase in amplitude, with both alpha and theta waves present. Stage 1 sleep typically lasts for a few minutes before transitioning into stage 2 sleep.