What Really Happens In Your Brain During Deep Sleep

Sleep takes up nearly one-third of a person’s life, yet many still wonder what really happens while we rest. Until the mid-20th century, scientists believed sleep was simply a time when the body and brain shut down. Research now shows that sleep is far from passive, it’s an active, restorative process essential for mental and physical health. As Johns Hopkins neurologist and sleep expert Dr. Mark Wu explains, the brain remains deeply engaged during sleep, performing vital tasks that influence memory, mood, and overall well-being.The Stages of SleepExperts say the human sleep cycle has four main stages that repeat throughout the night. The first three make up non-rapid eye movement (non-REM) sleep, while the fourth is REM sleep, the stage most closely linked with dreaming.In the first stage