Study design and settings
This cross-sectional analytical study was conducted on young women (12–25 years) residing in Beni-Suef City in Upper Egypt during the period between August 2016 and April 2017. Beni-Suef City is an urban metropolitan occupied surrounded by rural villages.
Sample size calculation
The sample size was calculated using the Epi-Info version 7 StatCalc, which is available from the Centers for Disease Control (CDC) and the World Health Organization (WHO). After reviewing previously published reports, we chose the following: a confidence level of 95% and a margin of error of 5%. In order to overcome the expected low response rate, we more than tripled the least required sample size.
In this study, a multi-stage random technique was adopted. First, we classified the urban metropolitan to 3 socio-economic strata: low, middle, and high. Then, out of each stratum, we selected 2 quarters by card withdrawal, and out of each quarter, almost 100 households were chosen using a random start. Later, we stratified the rural villages geographically to North, West, and South villages, and 2 villages were selected by card withdrawal from each direction. The 6 selected villages were further clustered roughly to 3 areas, and their residents were asked to participate in the study. Eventually, a total of 6000 young women (3600 from urban areas and 2400 from rural areas) were invited to participate after the householders were briefed on the purpose and steps of the study.
Young women who showed their readiness to participate were asked to sign their informed consents while the guardians of young women < 18 years were asked to sign on behalf of their daughters. In addition to the acceptance of their guardians, young women < 18 years were required to give their verbal assent before participation. The study protocol was approved by the Research Ethics Committee of Beni-Suef University.
We interviewed all young women who experienced a menstrual period at least for 1 year using an Arabic questionnaire comprised of four sections. The first section included socio-demographic questions: age, education or work, marital status, residence, parental education, physical activity, exposure to passive smoking, and preference for salty-fatty food. The second section included gynecological history questions: circumcision, the age of menarche, menstrual flow days, and menstrual cycle duration. The third section included questions about premenstrual symptoms and dysmenorrhea during the previous 6 months. The premenstrual symptoms were defined as physical and emotional symptoms experienced within 7 to 10 days before menstruation. These symptoms included spasm, fatigue, headache, irritation or nervousness, breast pain, GIT disturbance, and weight gain. Dysmenorrhea was defined as a painful cramping sensation in the groin during flow days. The fourth section assessed the average hours of sleep per day in addition to insomnia during the previous 6 months. Insomnia was defined as a difficulty to initiate or maintain sleep. A scale of never, rarely, sometimes, and always was used to assess the presence of insomnia.
We used the software Statistical Package for Social Science (SPSS Inc. Released 2009, PASW Statistics for Windows, version 18.0: SPSS Inc., Chicago, IL, USA) for statistical analysis. Binary logistic regression analyses were conducted to determine whether sleeping < 8 or < 7 or < 6 h/day in reference to sleeping ≥ 8 h and insomnia versus never to rarely insomnia could be associated with different premenstrual symptoms and dysmenorrhea. Only those who reported insomnia by the choices sometimes or always were considered having insomnia. The following covariates were included in the regression models: gynecological age (chronological age-age of menarche), residence, educational and occupational status, marriage, parental education, passive smoking, diet, and circumcision. The manuscript was reported according to the STROBE checklist (Additional file 1).