NT1 is characterized by 5 symptoms^1,5:

• Excessive daytime sleepiness (EDS): persistent sleepiness, tiredness, or fatigue that can return quickly after sleep or naps
• Cataplexy: the sudden and temporary loss of muscle tone
• Disrupted nighttime sleep: poor sleep quality due to a lack of sleep continuity
• Hallucinations: vivid, dreamlike states (auditory or visual) that happen when falling asleep or immediately when waking up
• Sleep paralysis: the inability to move when falling asleep or immediately after waking up, which is caused by the intrusion of rapid eye movement (REM) sleep into the wake state

Cataplexy—the sudden and temporary loss of muscle tone—is a hallmark symptom of narcolepsy type 1 (NT1). It can happen any time that rapid eye movement (REM) sleep intrudes into the awake state and can be brought on by laughter or strong emotions, such as elation or anger. Cataplexy can be localized, such as to the limbs, head, or neck, or affect the entire body.⁶

Manifestations of cataplexy can be different in each person, especially between children and adults. Some people with narcolepsy type 2 (NT2) will develop cataplexy later in their disease, making the identification of this symptom critical, but difficult.⁶

The hallmark symptoms of NT1—excessive daytime sleepiness (EDS), cataplexy, disrupted nighttime sleep, hallucinations, and sleep paralysis—have been shown to negatively affect patients’ quality of life. The effects of NT1 can extend across a range of normal daily functioning, including^1,7-9:

• Not feeling well rested and refreshed
• Difficulty enjoying everyday activities, like exercise
• Struggling to overcome the cognitive impairment that makes work or school difficult
• Trouble building or maintaining relationships
• Difficulty managing everyday responsibilities, like parenting, cooking, cleaning, and self-care

Narcolepsy type 1 is thought to be caused by a disruption of orexin signaling, which regulates the sleep-wake cycle. Orexin, also known as hypocretin, is a neuropeptide released by orexinergic neurons located in the hypothalamus. It is responsible for stabilizing the sleep-wake cycle. Orexin neuropeptides project deep throughout the brain to regions involved in cognition and attention, mood, muscle tone, and energy.^2,3,5

Orexin, also known as hypocretin, is a neuropeptide released by orexinergic neurons located in the hypothalamus. It is responsible for stabilizing the sleep-wake cycle. Orexin neuropeptides project deep throughout the brain to regions involved in cognition and attention, mood, muscle tone, and energy.^2,3,5