What substance is most commonly associated with Monday morning sickness?

Monday morning sickness refers to the phenomenon where individuals who are not exposed to certain substances during the weekend experience withdrawal symptoms when they return to a work environment on Monday. This term is often associated with the consumption of nitrates used in some industrial settings, particularly in the context of workers who may be exposed to nitroglycerin or other nitrate compounds.

When individuals who regularly handle nitrates are suddenly not exposed over the weekend, they may experience withdrawal symptoms by Monday. Those symptoms can include headaches and various discomforts, effectively termed "Monday morning sickness." This specific association highlights the impact of nitrates on the body, primarily in occupational settings.

In contrast, while caffeine, alcohol, and nicotine can have withdrawal effects, they are not specifically termed the same way nor directly linked to this particular phenomenon. Caffeine withdrawal can lead to headaches and fatigue, but it does not have the same occupational link that nitrates do with Monday morning sickness. Thus, nitrates stand out as the correct answer for this context.