Final answer:
Narcolepsy is the sleep disorder that includes uncontrollable sleep attacks which may start in REM sleep. It can feature cataplexy, hallucinations, and sleep paralysis.
Step-by-step explanation:
The sleep disorder characterized by uncontrollable sleep attacks, often beginning in REM sleep and occurring at inopportune times, is known as narcolepsy. People with narcolepsy can experience episodes so intense that they fall asleep suddenly, regardless of what they are doing.
Along with excessive daytime sleepiness, narcolepsy can also involve cataplexy (a sudden loss of muscle tone), sleep paralysis, and vivid hallucinations. The episodes can be triggered by heightened emotions and may last from a few minutes to half an hour, after which the person might feel refreshed.