Which sleep stage and type represents the lowest heart rate and respiratory rate?

Stage 3, also known as non-REM sleep, is characterized by the deepest level of sleep. During this stage, both heart rate and respiratory rate are at their lowest compared to other sleep stages. This is a restorative phase where the body is in a state of complete relaxation, allowing for physical recovery and growth. The body undergoes critical repair processes, hormone regulation, and immune system strengthening. The physiological parameters, such as heart rate and respiratory rate, decrease significantly to help facilitate these restorative functions.

In contrast, light sleep (Stage 1) and moderate sleep (Stage 2) generally have higher heart and respiratory rates compared to non-REM Stage 3. REM sleep, while it is a stage in which dreaming occurs, also exhibits a more variable heart rate and respiratory pattern due to increased brain activity, leading to parameters that are not as low as in non-REM sleep. Thus, Stage 3 (non-REM) undeniably represents the lowest heart and respiratory rates during the sleep cycle.