Clue: Sleep stage, initially

Answer: REM

Length: 3

---

Similar Clues:

• Crucial sleep stage (REM with 3 letters)
• Stage of sleep, for short (REM with 3 letters)
• Sleep stage, briefly (REM with 3 letters)
• Sleep-stage acronym (REM with 3 letters)
• Sleep-stage letters (REM with 3 letters)
• Sleep stage letters (REM with 3 letters)
• Sleep stage: Abbr. (REM with 3 letters)
• Sleep stages (REMS with 4 letters)
• Deep sleep stages (REMS with 4 letters)
• Sleep stage (REM with 3 letters)