How long does NREM Stage 1 typically last when a person first enters sleep?

NREM Stage 1 is the transitional phase between wakefulness and sleep and typically lasts about 5 to 10 minutes when a person first enters sleep. During this stage, individuals may experience light sleep, where they can be easily awakened, and there can be some muscle activity as well as fleeting thoughts. This stage serves as a brief period to prepare the body for deeper stages of sleep, where restorative processes can occur.

While the other options suggest longer durations for this initial stage, it's well established that the first stage of non-rapid eye movement (NREM) sleep is indeed fairly short, making 5 to 10 minutes the most accurate characterization of this early phase. The subsequent stages of NREM sleep tend to increase in duration, especially as the night progresses, but Stage 1 is characterized by its brevity.