Medically reviewed by Sanja Jelic, MD Key Takeaways The sleep cycle has three NREM stages and one REM stage.Deep sleep occurs in stage 3 and is crucial for feeling refreshed.REM sleep helps in ...

Here's what happens during each stage of labor – from how long each stage lasts to what you might feel. Labor happens in three stages — early labor and dilation, pushing and delivery, and finally, ...