Which set correctly lists the four sleep stages including REM?

Which set correctly lists the four sleep stages including REM?

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

Answer: (C)

Understanding sleep architecture means recognizing four stages: N1, N2, N3, and REM. A typical sleep cycle moves from lighter sleep to deeper sleep and then into REM. The natural progression is N1 → N2 → N3 → REM, so a list showing those four stages in that order is the correct one. N1 is a light transition into sleep; N2 adds sleep spindles and a deeper drop in consciousness; N3 is the deepest, slow-wave sleep; REM is when dreaming occurs and brain activity resembles wakefulness while the body experiences muscle atonia. The other sequences mix REM with the non-REM stages or reorder them, which doesn’t match how a standard sleep cycle unfolds.

Understanding sleep architecture means recognizing four stages: N1, N2, N3, and REM. A typical sleep cycle moves from lighter sleep to deeper sleep and then into REM. The natural progression is N1 → N2 → N3 → REM, so a list showing those four stages in that order is the correct one. N1 is a light transition into sleep; N2 adds sleep spindles and a deeper drop in consciousness; N3 is the deepest, slow-wave sleep; REM is when dreaming occurs and brain activity resembles wakefulness while the body experiences muscle atonia. The other sequences mix REM with the non-REM stages or reorder them, which doesn’t match how a standard sleep cycle unfolds.