Final answer:
Each cycle of sleep during a full night's sleep lasts approximately 90 minutes.
Step-by-step explanation:
The correct answer is (B) 90 minutes.
During a full night's sleep, typically consisting of multiple sleep cycles, each cycle lasts approximately 90 minutes. Each cycle is composed of different stages of sleep, including non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.
In NREM sleep, there are three stages: stage 1, stage 2, and stage 3. The stages progress from lighter to deeper sleep. Stage 3 is also known as slow-wave sleep.
REM sleep is the stage where dreaming occurs and the brain is very active. It is characterized by rapid eye movements and muscle paralysis. REM sleep typically occurs about 90 minutes after falling asleep and repeats multiple times throughout the night.