Associations of chronotype and insomnia with menstrual problems in newly employed nurses at university hospitals in the Republic of Korea

Han-Na Jung; Dongwhan Suh; Woo Chul Jeong; Jia Ryu; Yu-Mi Kim; Seohyun Yoon; Hyunjoo Kim

doi:10.35371/aoem.2023.35.e30

Associations of chronotype and insomnia with menstrual problems in newly employed nurses at university hospitals in the Republic of Korea

Ann Occup Environ Med. 2023 Aug 4:35:e30. doi: 10.35371/aoem.2023.35.e30. eCollection 2023.

Authors

Han-Na Jung¹, Dongwhan Suh¹, Woo Chul Jeong¹, Jia Ryu², Yu-Mi Kim^{3

4}, Seohyun Yoon⁵, Hyunjoo Kim¹

Affiliations

¹ Department of Occupational and Environmental Medicine, Ewha Womans University Mokdong Hospital, Seoul, Korea.
² Department of Occupational and Environmental Medicine, Catholic Kwandong University International St. Mary's Hospital, Incheon, Korea.
³ Department of Preventive Medicine, College of Medicine, Hanyang University, Seoul, Korea.
⁴ School of Public Health, Hanyang University, Seoul, Korea.
⁵ Ewha Medical Research Institute, Ewha Womans University School of Medicine, Seoul, Korea.

Abstract

Background: Dysmenorrhea and menstrual cycle changes occur in women working shifts. Circadian rhythm disruption and sleep disturbances associated with shift work leads to health problems. We identified chronotypes and the occurrence of insomnia among newly employed university hospital nurses and investigated the association of these factors with menstrual problems.

Methods: We conducted pre-placement health examinations for shift workers using self-reported questionnaires between 2018 and 2020. A total of 463 nurses were included in the study. Sociodemographic data, shift work experience, and information on insomnia were collected from health examination data. In addition, details regarding chronotype, dysmenorrhea, irregular and abnormal menstrual cycles, amenorrhea, and contraceptive use were obtained from the questionnaire. Multiple logistic regression analysis was performed to study the association between chronotype, insomnia, and menstrual problems after controlling for age, body mass index, contraceptive use, amenorrhea, and prior shift work.

Results: The prevalence rates of dysmenorrhea, irregular menstrual cycles, and longer menstrual cycles were 23.8%, 14.9%, and 4.1%, respectively. The risk of dysmenorrhea increased in the evening-type (odds ratio [OR]: 3.209; 95% confidence interval [CI]: 1.685-6.113) and those with insomnia (OR: 1.871; 95% CI: 1.074-3.261). Additionally, the risk of an irregular menstrual cycle (OR: 2.698; 95% CI: 1.167-6.237) increased in the evening-type, and the risk of a longer menstrual cycle (OR: 4.008; 95% CI: 1.354-11.864) increased in individuals with insomnia.

Conclusions: Our findings suggest that dysmenorrhea is promoted in the evening-type and insomnia individuals. There may be an increased risk of irregular menstrual cycles among evening-type nurses and an increased risk of longer menstrual cycles among those with insomnia. Therefore, factors such as evening-type and insomnia should be considered for the prevention of menstrual problems in women performing shift work.

Keywords: Chronotype; Circadian rhythm; Dysmenorrhea; Insomnia; Menstrual cycle; Nurse.