Association Between Loneliness, Premenstrual Symptoms, and Other Factors During the COVID-19 Pandemic: A Cross-Sectional Study with Japanese High School Students.

Adolescent females in Japan showed a high prevalence of loneliness. School year (2nd year), longer periods of internet use, premenstrual symptom severity, and psychological distress were independently associated with loneliness. For clinicians and school health professionals, special concern should be given to the psychological health of adolescent females during the COVID-19 pandemic.