Mapping nocturnal arousal across sleep and pain disorders

Narcolepsy is a chronic sleep disorder characterized by pervasive, uncontrolled sleepiness and other sleep disturbances. One of its hallmark symptoms is an abrupt transition to REM sleep upon falling asleep, which causes symptoms typically associated with this phase to occur unexpectedly during wakefulness. These include the following symptoms, which typically last from a minute or two to half an hour.

Sleep is an essential physiological process vital to maintaining overall well-being. The reticular activating system (RAS), a network of neurons in the brainstem, regulates wakefulness and sleep. While it may seem passive, sleep consists of distinct cycles, each with its unique characteristics and functions. Two key sleep phases are non-rapid eye movement (NREM) and  rapid eye movement (REM).
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:

Sleep, an essential biological state, involves significant reductions in physical activity, sensory awareness, and interaction with the environment. This complex physiological process is primarily regulated by specific brain regions, notably the hypothalamus and pons, which govern the sleep-wake cycle or circadian rhythm.
The circadian rhythm, a nearly 24-hour cycle, is deeply influenced by environmental light cues. Light exposure directly affects the hypothalamus, which in turn regulates...

Primary motives such as sleep, sex, and pain avoidance are crucial drivers of behavior in humans and animals. These motives ensure survival, reproductive success, and overall well-being by prompting actions that meet essential bodily needs.
Sleep is a fundamental physiological drive that fosters a state of restfulness crucial for several bodily functions. It facilitates body restoration, the process by which the body repairs, rejuvenates, and maintains itself during sleep, including memory...

The sleep cycle, an integral part of human health, consists of several stages with distinct characteristics and functions. It begins with a transition from wakefulness to sleep, known as the light sleep phase, followed by the restorative deep sleep phase, essential for physical recovery and growth. The cycle concludes with the Rapid Eye Movement (REM) phase, characterized by high brain activity and vivid dreaming. Insomnia, a prevalent sleep disorder, involves difficulty falling asleep, staying...

Nightmares and night terrors represent two distinct types of sleep disturbances that differ in timing, characteristics, and the sleeper's recall of the event. Nightmares are vivid, disturbing dreams that usually awaken the sleeper from REM sleep, a stage of sleep where brain activity is high, and dreams are most frequent. Upon awakening, individuals often have detailed recollections of their nightmares, which can include themes of threats to survival, security, or self-esteem.
Nightmares...