Title: "Prevalence of hot flushes and night sweats around the world: a systematic review"

Authors: Dr. Ellen W. Freeman & K. Sherif
Published: June 2007, Climacteric

The authors reviewed 66 epidemiologic studies (1966–2006), covering women aged ~40–65 across diverse regions—North America, Europe, Asia, Latin America, Middle East, Africa, and Australia.

Key Findings

1. High global prevalence, but variable

• Vasomotor symptoms (VMS: hot flushes/night sweats) occur in most societies.
• Prevalence depends heavily on menopausal stage:
  • Premenopause: median ~21.5% (range 3–86%)
  • Perimenopause: median ~41% (range 13–79%)
  • Postmenopause: median ~41.5% (range 8–80%)

2. Ethnicity & geography matter

• North America (SWAN study, 16,065 women):
  • Combined VMS rates: African‑American 46%, Hispanic 35%, Caucasian 31%, Chinese 21%, Japanese 18%.
  • Night sweats ranged: African‑American 32% down to Japanese 9%.
• East Asia: Rural Chinese reported much lower VMS (28%) than urban/professional women (~47%). Japanese and Chinese women generally reported the lowest rates; postmenopausal median was ~16%, compared with ~47% in Latin America and ~55% in Europe.
• Other regions: Australia (~55% in postmenopause), Latin America (~68% prematurity), Middle Eastern rates varied (Lebanon 10–20% higher than Morocco), Africa showed wide variation (e.g., Ghana 57% vs. Nigeria 23%) .

3. Sources of variability

• Methodological: differences in study design, populations, menopause definitions, rural vs urban settings.
• Sociocultural: attitudes toward aging/menopause, roles, reporting behavior.
• Biological factors: climate variations; higher rates in warmer regions, but inconsistency across studies.
• Lifestyle/diet: e.g., high soy intake in Japanese women proposed as protective; body mass index, smoking status may impact VMS frequency/severity.

Underlying Mechanisms

• Hormonal shifts: Estrogen fluctuations during perimenopause disrupt hypothalamic temperature regulation, narrowing the thermoneutral zone—making small changes trigger intense vasomotor responses.
• Neurotransmitters: Involvement of serotonin and norepinephrine in the brain’s thermal sensing pathways.

Clinical Implications

• VMS are globally common but vary based on biology, culture, and reporting habits.
• Clinicians must ask directly about hot flushes/night sweats—they often go unreported, especially in groups with lower reported prevalence.
• Women in perimenopause and early postmenopause are most likely to experience symptoms. Chronic VMS can last years, with significant impact on quality of life, sleep, mental health, and work.

✅ Summary Takeaway

Hot flushes and night sweats are widespread menopause-related symptoms. Their prevalence is highest in peri‑ and early postmenopause, but rates differ dramatically worldwide. These differences stem from physiological stages, cultural perceptions, study methods, and lifestyle factors. Estrogen decline disrupts temperature regulation, mediated by brain chemistry, causing VMS. Clinically, proactive screening and culturally sensitive questioning are essential to managing these symptoms effectively—and improving women's quality of life during midlife.