Montblack writes:

http://www.modafinil.com/
...modafinil ('Provigil', 'Alertec', 'Vigicer', 'Modalert', etc) is a
memory-improving and mood-brightening psychostimulant. It enhances
wakefulness and vigilance, but its pharmacological profile is notably
different from the amphetamines, methylphenidate (Ritalin) or cocaine.
Modafinil is less likely to cause jitteriness, anxiety, or excess locomotor
activity - or lead to a hypersomnolent 'rebound effect' - than traditional
stimulants. Subjectively, it feels smoother and cleaner than the
amphetamines too. It may even be anxiolytic.

Amphetamines were long the stimulant of choice for the military.