Which of the following is a sign of CNS stimulants abuse or overdose?

Hallucinations and seizures are significant indicators of central nervous system (CNS) stimulant abuse or overdose. CNS stimulants, such as cocaine or amphetamines, can cause excessive stimulation of the brain, leading to severe psychological and physiological effects. These effects may manifest as hallucinations, where an individual perceives things that are not actually present, and seizures, which are a result of the brain's heightened activity and can lead to convulsions.

In the context of overdose, the risk of these severe symptoms increases due to the overwhelming effects of the drugs on the neural pathways. Thus, experiencing hallucinations and having seizures are critical signs that indicate the potential for serious harm and the necessity for immediate medical attention.

Other options, such as increased appetite, significant weight gain, and enhanced sleeping patterns, are typically not associated with CNS stimulant abuse; in fact, these substances often lead to reduced appetite and insomnia in users.