When does narcolepsy start to affect person?

Any age: But usually in 20s to 30s. Polysomnogram (sleep study) and multiple sleep latency tests will help diagnose this condition for which a number of useful therapies are available.

Usually as teenager: Narcolepsy usually has its onset during the teenage years. However, it is common to take many years to actually make the diagnosis. Children as young as 4 have been diagnosed with this chronic condition.