As you sleep, your brain cycles through four stages of sleep.
– Stages 1 to 3 are what's considered
non-rapid eye movement (NREM) sleep,
also known as quiet sleep.
– Stage 4 is
rapid eye movement (REM) sleep
, also known as active sleep or paradoxical sleep.
Each has a unique function and role in maintaining your brain's overall cognitive performance
NREM Stage 1
The first stage of the sleep cycle is a transition period between wakefulness and sleep.
NREM Stage 2
According to the American Sleep Foundation, people spend approximately 50% of their total sleep time during NREM stage 2, which lasts for about 20 minutes per cycle.
NREM Stage 3
Deep, slow brain waves known as delta waves begin to emerge during NREM stage 3 sleep—a stage that is also referred to as delta sleep.
While your brain is aroused with mental activities during REM sleep, the fourth sleep stage, your voluntary muscles become immobilized.