Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness (EDS), cataplexy, sleep paralysis, hallucinations and disturbed nighttime sleep. Diagnosis is confirmed by polysomnography, MSLT and HLA DQ-B1 06*02 typing. Depressive symptoms are often associated. Neverthless, pseudo-narcolepsy is also reported in major depressive disorder (MDD).

We provide arguments to differentiate pseudo-narcolepsy associated to MDD and narcolepsy in young man with some complains of narcolepsy (EDS, muscular tonus inhibition, hallucinations) without amelioration by derived-amphetaminic treatment.

A better cognition of confounding symptoms in MDD and narcolepsy would help to better treatment.

A 26-year-old man was hospitalized during three successive night at Sleep Laboratory. Psychiatric interview, polysomnography, MSLT, 24h-recording, HLA-typing, projective test (Rorschach), Hamilton Depressive Scale, familial history were performed. Patient was treated by venlafaxine and support therapy during 6 months and then, evaluated by the same psychiatrist.

During all nights, polysomnography showed altered REM latency, largely decreased sleep efficiency and deep sleep while awake and stage 1 durations were increased. MSLT and HLA-typing were typical of narcolepsy but daytime sleeping was shortened. Psychiatric interview and Hamilton scale confirmed MDD. Somatisation and post-traumatic depression elements were pointed by Rorschach evaluation. Familial history reported physical abuse during childhood. Each symptom disappeared after 6 months.

In the absence of a clear history of narcolepsy, MDD would be excluded by extensive complementary evaluation.