Which stage is the deepest stage of sleep?

Which stage is the deepest stage of sleep?

• A. Stage N1
• B. Stage N2
• C. Stage REM
• D. Stage N3

Answer: (D)

Deep sleep in non-REM sleep is the deepest stage, called slow-wave sleep. On EEG this stage shows delta waves—high amplitude, very slow activity (around 0.5–4 Hz)—reflecting a highly synchronized brain. Because of this synchronization, your arousal threshold is the highest here, making it hardest to wake someone from this stage. Physically, the body slows significantly: heart rate and blood pressure drop, breathing becomes slower and more regular, and muscles have reduced tone (though not the complete paralysis seen in REM sleep). This deep stage mostly occurs in the first part of the night and diminishes in later cycles. REM sleep is different—dreaming and eye movements with wake-like brain activity, but it isn’t the deepest stage. So the deepest stage is Stage N3.

Deep sleep in non-REM sleep is the deepest stage, called slow-wave sleep. On EEG this stage shows delta waves—high amplitude, very slow activity (around 0.5–4 Hz)—reflecting a highly synchronized brain. Because of this synchronization, your arousal threshold is the highest here, making it hardest to wake someone from this stage. Physically, the body slows significantly: heart rate and blood pressure drop, breathing becomes slower and more regular, and muscles have reduced tone (though not the complete paralysis seen in REM sleep). This deep stage mostly occurs in the first part of the night and diminishes in later cycles. REM sleep is different—dreaming and eye movements with wake-like brain activity, but it isn’t the deepest stage. So the deepest stage is Stage N3.