Which of the following is a side effect of stimulants?

In the context of stimulant medications, increased energy and focus is a well-documented and expected side effect. Stimulants function primarily by enhancing the activity of certain neurotransmitters in the brain, such as dopamine and norepinephrine. This increased neurotransmitter activity is what leads to heightened alertness, greater attention span, and improved concentration, which are essential for individuals diagnosed with attention-deficit hyperactivity disorder (ADHD) and other related conditions.

On the other hand, the other options reflect effects or side effects that are not typically associated with stimulant use. For instance, depression is more commonly associated with withdrawal from stimulants rather than their use. Pinpoint pupils are associated with opioids rather than stimulants, and calming effects are typically seen with depressants rather than stimulants. Therefore, the answer that reflects a true side effect of stimulants is increased energy and focus.