Final answer:
There are three stages of NREM sleep, and respiration decreases dramatically during stage 3, which is also known as deep sleep or slow-wave sleep.
Step-by-step explanation:
Non-Rapid Eye Movement (NREM) sleep is divided into three stages. In the first stage of NREM sleep, which is stage 1, there is a slowdown in both the rates of respiration and heartbeat. As we progress into deeper stages of NREM sleep, specifically stage 3, which is often called deep sleep or slow-wave sleep, an individual's heart rate and respiration decrease dramatically.
This stage is characterized by low frequency, high amplitude delta waves, and it is more difficult to awaken someone from stage 3 sleep.In stage 3 sleep, also known as deep sleep, an individual's heart rate and respiration decrease dramatically.