Final answer:
Norepinephrine is the neurotransmitter responsible for arousal and maintaining attention, which can lead to sleeplessness. It acts on adrenergic receptors and is released by the adrenal medulla and in the central nervous system, playing a vital role in the body's stress response and vigilance mechanisms.
Step-by-step explanation:
The substance responsible for arousal and maintaining attention, which can lead to sleeplessness, is C) Norepinephrine. This neurotransmitter acts upon α- or β-adrenergic receptors, influencing physiological responses that are part of the body's fight-or-flight response. Norepinephrine is released both as a hormone from the adrenal medulla and as a neurotransmitter in the central nervous system. Its release is triggered by stress, among other factors, and it plays a key role in arousal and vigilance.
Acetylcholine (ACh) is another neurotransmitter involved in attention and arousal, besides its vital function at motor end-plates causing muscular depolarization. However, when considering the options provided, and the fact that norepinephrine has a more direct role in sleeplessness, norepinephrine is the correct answer.
It is important to note that serotonin is also a monoamine neurotransmitter but is more commonly associated with mood regulation and sleep cycle modulation. Histamine plays diverse roles in the body including immune responses and gastric acid secretion, but is not the primary factor in sleeplessness regarding the options given.