In narcolepsy, the reflex inhibition of the motor system seen in cataplexy has features normally seen only in normal REM sleep. Diagnosis
The third edition of the International Classification of Sleep Disorders (ICSD-3) differentiates between narcolepsy with cataplexy (type 1) and narcolepsy without cataplexy (type 2), while the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) uses the diagnosis of narcolepsy to refer to type 1 narcolepsy only. The DSM-5 refers to narcolepsy without cataplexy as hypersomnolence disorder. The most recent edition of the International Classification of Diseases, ICD-11, currently identifies three types of narcolepsy: type 1 narcolepsy, type 2 narcolepsy, and unspecified narcolepsy.ICSD-3 diagnostic criteria posits that the individual must experience "daily periods of irrepressible need to sleep or daytime lapses into sleep" for both subtypes of narcolepsy. This symptom must last for at least three months. For a diagnosis of type 1 narcolepsy, the person must present with either cataplexy, a mean sleep latency of less than 8 minutes, and two or more sleep-onset REM periods (SOREMPs), or they must present with a hypocretin-1 concentration of less than 110 pg/mL. A diagnosis of type 2 narcolepsy requires a mean sleep latency of less than 8 minutes, two or more SOREMPs, and a hypocretin-1 concentration of more than 110 pg/mL.
This can feel like living their entire lives in a constant state of sleep deprivation.Excessive sleepiness can vary in severity, and it appears most commonly during monotonous situations that dont require much interaction. Daytime naps may occur with little warning and may be physically irresistible. These naps can occur several times a day. They are typically refreshing, but only for a few hours or less. Vivid dreams may be experienced on a regular basis, even during very brief naps. Drowsiness may persist for prolonged periods or remain constant. In addition, night-time sleep may be fragmented, with frequent awakenings. A second prominent symptom of narcolepsy is abnormal REM sleep. Narcoleptics are unique in that they enter into the REM phase of sleep in the beginnings of sleep, even when sleeping during the day.The classic symptoms of the disorder, often referred to as the "tetrad of narcolepsy," are cataplexy, sleep paralysis, hypnagogic hallucinations, and excessive daytime sleepiness. Other symptoms may include automatic behaviors and night-time wakefulness. These symptoms may not occur in all people with narcolepsy. Cataplexy is an episodic loss of muscle function, ranging from slight weakness such as limpness at the neck or knees, sagging facial muscles, weakness at the knees often referred to as "knee buckling", or inability to speak clearly, to a complete body collapse. Episodes may be triggered by sudden emotional reactions such as laughter, anger, surprise, or fear. The person remains conscious throughout the episode. In some cases, cataplexy may resemble epileptic seizures.