(parts taken from How does your engine run?: A leader’s guide to the Alert Program for self-regulation, Mary Sue Williams & Sherry Shellenberger, 1994)
Arousal can be considered a state of the nervous system describing how alert one feels. In order to attend, concentrate, and perform tasks in a manner suitable to the situational demands, one’s nervous system must be in an optimal state of arousal for that particular task. Self-regulation is the ability to attain, maintain, and change arousal appropriately for a task or situation. Most individuals self-regulate their arousal levels throughout the day, with no conscious thought or effort. In the morning when they wake up, they are able to move from a low arousal state (sleep) to an optimal level so they can focus on the day’s activities. And when the day is done, they are able to move back down to a low arousal state in order to fall asleep.
Arousal levels can mildly fluctuate throughout the day in response to various sensory events (ex. a car honking on the freeway or burning a hand on a hot pan may momentarily startle, eating too much for lunch may produce a brief food coma) , but most individuals are usually able to self-regulate so that their arousal stays within an optimal zone. Some individuals, however, are unable to self-regulate their arousal level and may 1) have low arousal throughout the day (ex. cannot seem to get going, lethargic, slow, usually sedentary), 2) have high arousal throughout the day (ex. seems unable to calm down, hyperactive, seemingly minor incidents result in major meltdowns, fight or flight response, becomes overwhelmed and freezes or shuts down), or 3) have large fluctuations throughout the day ranging from very low to very high arousal.