Introduction: Bariatric surgery is the mainstay of treatment of obesity, with a proven, long-lasting effect on body weight reduction and remission of co-morbidities. Sleep disorders, including insomnia, and deteriorated sleep quality and duration are associated with obesity, and a reduction in body weight can be associated with a reduction in prevalence of sleep disorders. The purpose of this study was to assess the influence of laparoscopic sleeve gastrectomy (LSG) on the prevalence and intensity of different sleep disturbances. Methods: This observational prospective study included 80 patients qualified for bariatric surgery who filled in a questionnaire with a set of structured questions about different sleep disturbances, such as difficulties in falling asleep, night awakenings, early morning awakenings, snoring, and nightmares, as well as eating at night and daytime dysfunction, supplemented with Athens Insomnia Scale (AIS), before and 6 months after bariatric surgery. Results: There was a statistically significant reduction in incidence of night awakenings, with 40.00% of participants reporting night awakenings before surgery and, respectively, 25.00% after surgery. A significant reduction was also observed in the rate of patients who reported snoring, with 60.00% before the surgery and 38.75% after the surgery (p < 0.05). There was a correlation present between estimated weight loss % (EWL%) and reduction in snoring (p < 0.05). The mean total AIS score before surgery was 7.21 and 5.99 after surgery, and the change was statistically significant (p < 0.05). A total AIS score of 8 or more, the cutoff score for insomnia diagnosis according to the Polish validation of the Athens Insomnia Scale, was present in 44.16% of cases before surgery and in 38.00% after surgery (p = 0.52). There was a significant difference in the incidence of awakening during the night score before and after surgery (p < 0.05; CI 0.022–0.341), sleep quality (p < 0.05; CI 0.0105–0.4311), well-being during the day (p < 0.05; CI 0.0273–0.4143), and sleepiness during the day (p < 0.05; CI 0.101–0.444). Conclusions: LSG is observed to have a positive effect on selected sleep disturbances and insomnia remission in patients with obesity, measured by a significant reduction in Athens Insomnia Scale scores in follow-up 6 months after surgery. Additionally, patients after bariatric surgery reported less night awakenings and there was a lower rate of snoring. Therefore, LSG can be considered an effective therapeutic tool for insomnia in patients with obesity.
