Insomnia negatively impacts person's quality of life. Little is known about its relationship with gastroesophageal reflux disease (GERD) and body mass index (BMI). Objectives were to evaluate the prevalence of insomnia among primary care adult population; explore its associated factors; examine the relationship between insomnia and BMI categories, and GERD and to ascertain daytime impairments of patients with insomnia. In a survey, representative sample of primary care adult population was screened using questionnaire consists of the following parts: sociodemographic characteristics; habits; validated Arabic versions of Athens insomnia scale, Epworth sleepiness scale, fatigue severity scale and GerdQ questionnaire; participants' height and weight. Out of 3166 surveyed, 1903 suffered insomnia with a prevalence of 60.1%. Through multivariable analysis, insomnia was significantly higher among people having insufficient income (aOR = 1.95), smokers (aOR = 1.47), those drinking >3 coffee cups a day (aOR = 1.24), those having underweight (aOR = 2.06), and those suffering from; chronic disease (aOR = 1.25), fatigue (aOR = 2.10), daytime sleepiness (aOR = 1.57) and GERD (aOR = 1.65). In conclusion, insomnia is a prevalent problem among primary care population. Underweight, chronic diseases and GERD are associated factors. Daily impairment is a significant problem among insomnia patients.