Seizure occurrence in epilepsy is governed by biological rhythms, challenging the traditional view of seizures as random events. Circadian and multidien cycles shape seizure risk, with patient-specific chronotypes and stable temporal patterns observed across epilepsy types. The Molecular Oscillations and Rhythmicity of Epilepsy hypothesis posits that molecular oscillations-particularly those involving core clock genes and region-specific protein expression-create dynamic windows of increased seizure susceptibility. In epilepsy, these rhythms are altered, amplifying seizure risk through metabolic and genetic reorganization. Seizure timing is also modulated by hormonal cycles in women with catamenial epilepsy. Estrogen promotes seizures, while progesterone and its metabolite allopregnanolone are protective. Three distinct catamenial patterns guide diagnosis and treatment, though evidence for hormonal therapies remains limited. Personalized approaches, including adjunctive medications and cycle-specific dosing, may reduce seizure burden. Importantly, sudden unexpected death in epilepsy predominantly occurs at night, implicating sleep, circadian timing, and environmental factors. Nocturnal vulnerability is conserved across species, suggesting a biological mechanism potentially involving serotonin, which regulates respiration, cardiac function, and arousal. Finally, chronotherapeutic approaches offer a promising avenue for epilepsy management by aligning treatment with seizure timing. Time-adjusted dosing of antiseizure medications has shown improved outcomes in patients with predictable seizure patterns. Future strategies may include closed-loop systems and biomarker-guided interventions to shift seizure susceptibility rhythms. Together, these findings underscore the importance of temporal biology in epilepsy. Understanding when seizures occur provides insight into why they occur, paving the way for personalized, rhythm-informed care that enhances prediction, prevention, and treatment.