Sleep stages: a quick overview

Sleep is a complex process characterized by stages that repeat in a cyclical pattern throughout the night. These stages are categorized into two main types - rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. Each type is associated with unique brain activity and physiological processes.

NREM sleep can be further divided into three stages:

• NREM Stage 1, which is the initial stage of sleep that lasts just a few minutes and is when you feel relaxed and drowsy. Eye movement slows down and muscles start to relax.
• NREM Stage 2, which comprises the majority of sleeping time and is more restful than Stage 1.
• NREM Stage 3, which is also known as slow-wave sleep, is when the body repairs and regenerates. It’s hard to wake up when you’re in this phase of sleep, and brain activity shows up as delta waves on an EEG.

REM sleep is characterized by rapid eye movements and is the stage of sleep in which you dream. During this phase, the skeletal muscles are almost paralyzed, but the brain is highly active.