What condition could be suspected if a sleep study reveals significant daytime sleepiness and sudden muscle weakness?

The symptoms of significant daytime sleepiness and sudden muscle weakness strongly indicate narcolepsy. This neurological disorder is characterized by excessive daytime sleepiness and can include episodes of cataplexy, which is a sudden loss of muscle tone triggered by strong emotions. During these episodes, individuals may experience weakness in their legs, or even a complete collapse, while being fully aware of their surroundings.

Narcolepsy is also associated with disrupted sleep patterns, where individuals may fall asleep during the day at inappropriate times. This condition contrasts significantly with obstructive sleep apnea, insomnia, and restless legs syndrome. While obstructive sleep apnea may contribute to daytime sleepiness due to disrupted nighttime breathing, it does not typically present with the sudden muscle weakness seen in narcolepsy. Insomnia primarily involves difficulty falling or staying asleep, leading to daytime fatigue but not to the same extent of cataplexy. Restless legs syndrome causes uncomfortable sensations in the legs, often leading to difficulty falling asleep, but does not involve marked sleepiness or muscle weakness. Thus, the combination of excessive daytime sleepiness and episodes of muscle weakness is most indicative of narcolepsy.