Narcolepsy is a chronic sleep disorder that affects the brain's ability to regulate sleep-wake cycles. People with narcolepsy often experience excessive daytime sleepiness, which can lead to sudden sleep attacks during the day. These episodes can occur at any time, making it difficult for individuals to stay awake and alert. In addition to daytime sleepiness, narcolepsy may also cause other symptoms, such as cataplexy, which is a sudden loss of muscle tone triggered by strong emotions. Other symptoms can include sleep paralysis and vivid hallucinations during sleep transitions. Treatment typically involves lifestyle changes and medications to help manage symptoms.