Polysomnography is performed on a 46-year-old man with severe early-morning-waking depression, marked anhedonia, and weight loss. Which finding would best support classification as endogenous (melancholic-type) depression?

• A Prolonged REM latency greater than 120 minutes
• B Shortened REM latency under approximately 60 minutes ✓
• C Increased proportion of slow-wave (stage N3) sleep
• D Reduced total REM density

Explanation

Endogenous or melancholic depression characteristically produces cholinergic-dominant sleep architecture changes: shortened REM latency (often below 60 minutes), increased REM density, and reduced slow-wave sleep with impaired sleep continuity. These changes persist into remission in some patients and are not explained by drugs. Option A describes the opposite of the classic finding, and increased slow-wave sleep contradicts the well-replicated reduction seen in these patients.

Reference: Kaplan and Sadock's Synopsis of Psychiatry, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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