Circadian Rhythm Disruption and Hypothalamic–Pituitary–Ovarian Axis Dysregulation Following Transmeridian Travel: A Narrative Review

Introduction and aimMenstrual cycle irregularities are frequently reported by women exposed to circadian rhythm disruption, including frequent time-zone travelers and night/rotating shift workers. This narrative review evaluates evidence on how time zone change–related circadian misalignment may affect menstrual cycle regularity and female reproductive health. Materials and methodsLiterature was identified primarily in PubMed and supplemented by other accessible sources. We included randomized and crossover studies when available, and summarized epidemiological findings from questionnaire-based studies and selected systematic reviews. SummaryReported associations between circadian rhythm disruption and menstrual cycle irregularities appear to be modified by psychosocial stress, disrupted meal timing (chrononutrition), and endocrine disturbances such as hyperprolactinemia and altered diurnal cortisol rhythms. Mechanistically, the suprachiasmatic nucleus (SCN) and melatonin are key components linking circadian timing to reproductive regulation. ConclusionsCircadian-related menstrual disturbances, including those after abrupt time-zone shifts, may be underrecognized by patients and clinicians. More studies are needed in high-risk groups such as flight attendants and frequent travelers. Clinical assessment should also consider comorbid endocrine and sleep disorders and disordered/restrictive eating.