Restlessness and poor sleep quality are common complaints among patients undergoing bowel preparation for colonoscopy. However, their effect on preparation quality is not well defined. Our aim was to evaluate which sleep variables are associated with an adequate bowel preparation. Adequate preparation was defined as a score of 6 or higher on the Boston Bowel Preparation scale.

A multicenter, cross-sectional study was conducted in adult patients with an indication for colonoscopy. Bowel preparation was performed with a complete dose of polyethylene glycol (PEG). Face-to-face questionnaires were applied using dichotomous questions. Variables evaluated included falling asleep, trouble staying asleep, waking up during the night, sleeping more than 7 hours, and waking up restless. Those who showed no disturbances across all variables were defined as having good sleep quality. A multivariate logistic regression analysis was performed to identify predictors related to good sleep quality and adequate bowel preparation (Boston ≥ 6).

A total of 316 patients were included: 195 female (61.7%), age 50 ± 14. Adequate bowel preparation was in 140 (47.78%), and good sleep quality was in 32 (10.92%). In the logistic regression analysis, the only variable associated with adequate bowel preparation (Boston ≥6) was not having difficulty staying asleep (OR = 1.771; 95% CI: 1.125-2.787; p = 0.013) while in the multivariate analysis showed that those having difficulty maintaining sleep were significantly associated with having a junior-high education (OR = 3.395; 95% CI: 1.045–11.024; p = 0.042), and those patients who consumed cold PEG were more likely to report good sleep quality (OR = 0.593; 95% CI: 0.375–0.938; p = 0.025).

Sleep quality appears to play an important role in achieving adequate bowel preparation, possibly reflecting how closely patients follow instructions. Our findings show that the absence of nighttime awakenings—particularly difficulty staying asleep—is associated with better preparation quality. Notably, consuming the PEG solution cold was positively associated with sleep quality across all evaluated domains, suggesting a simple, practical opportunity for future preparation recommendations.