Pupil dilation (mydriasis) and involuntary semen discharge are distinct physiological events that share a common regulatory framework involving the autonomic nervous system and neuroendocrine signaling. Both responses are significantly influenced by sympathetic nervous system activation and modulation by key hormones and neurotransmitters. This review summarizes the mechanistic pathways linking these phenomena, emphasizing the role of catecholamines, androgens, and central neurotransmitters. Understanding this interconnection provides insight into normal physiological reflexes and helps differentiate them from pathological conditions.