Narcolepsy is an inherited disorder affecting Labrador retrievers. Dogs with the inherited form of narcolepsy typically present between one to six months of age with an inability to stay awake for extended periods of time and episodes of collapse and sleep following positive stimulation such as play or food. Affected dogs fall asleep faster than normal dogs and appear sleepy more frequently. During episodes of collapse dogs have a sudden loss of muscle tone and appear uncontrollably sleepy but may or may not completely fall asleep. Symptoms do not progress after one year of age and affected dogs do not have other associated health problems.