Which of the following is a psychophysical indicator of CNS stimulant use?

Loss of appetite is a recognized psychophysical indicator of Central Nervous System (CNS) stimulant use. CNS stimulants, such as amphetamines or cocaine, typically lead to a decrease in appetite as these substances can heighten energy levels and increase metabolic rate, leading to reduced feelings of hunger. This effect can also be linked to the way stimulants increase dopamine levels, which may suppress the body's natural hunger signals.

The other options describe effects that are generally contrary to the typical physiological and psychological responses associated with stimulant use. For example, decreased heart rate and increased sleepiness are more characteristic of depressant substances rather than stimulants, which generally increase heart rate and have a stimulating effect on the central nervous system. Heightened sense of taste, while it could be affected by various substances, is not a typical psychophysical indication of stimulant use specifically.