Stages 3 & 4: Deepest sleep, heart rate and breathing slow down as well as brain waves.
{"Image DocumentName": "Stages 3 & 4: Deepest sleep, heart rate and breathing slow down as well as brain waves.", "Image ImageDescription": "Delta waves appear. Deepest point about 30 min after beginning sleep cycle. Stage 4 ends when electrical activity increases. Sleeper starts back into sleep cycle starting with stage 3, then 2 etc.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}