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Definition - What does Sleep Stage 3 mean?

Stage 3 of the sleep cycle is known as deep, non-REM sleep, lasting 5-15% of the total sleep cycle. Stage 3 is characterized by a delta wave brain activity, known as slow waves. These brain waves develop restoration in the body, with the lowest levels of heart rate and breathing. In this stage, sleep disruptions are rare because the external stimulus is less intrusive. If awakened in this stage, it is common for individuals to experience a sense of disorientation.

SureHire explains Sleep Stage 3

Nightly sleep cycles oscillate between four stages. Each sleep stage generally lasts for 5-15 minutes, with an entire cycle taking 90-110 minutes cycling back to stage 3. Stage 3 is a deep sleep that prepares the body to enter REM cycle, where dreaming occurs. During Stage 3 of the sleep cycle, the body repairs muscle tears, grows tissue, builds muscle and stabilizes the immune system. Parasomnias are common in this cycle, experienced as sleep-walking, bedwetting, sleep-talking and night terrors.