A friend asked if coffee really helps to keep you awake. He has been transferred to the night shift and cannot help falling asleep while on duty.
What I know is that one of the stimulants common to most of our lives is caffeine found in coffee, tea, and some cola drinks. Stronger, more dangerous stimulants included in this category are the amphetamines, the family of drugs sometimes called "uppers" or "speed." Drugs of this type stimulate the central nervous system. They increase arousal and attention so that the user remains alert and wakeful, even though long hours without sleep. Powerful stimulants initially promote feelings of paranoid fears, and auditory hallucinations. As with other hand drugs, users develop a tolerance for amphetamines and they must be taken in larger and larger doses to achieve the euphoria that is sought. Not much is known about how these drugs work in the body.
Aha! sleeping at work, ha!