Association between sleep duration on the night before surgery and postoperative cognitive function: a prospective cohort study (Preprint)

BACKGROUND As the world is rapidly aging, and the number of elderly patients who undergo surgery is rising, postoperative cognitive dysfunction (POCD) among those patients has become an increasing healthcare problem. Although understanding risk factors and mechanisms underlying the pathogenesis of POCD is critically important from a preventative viewpoint, such knowledge and evidence are lacking. A growing body of evidence suggest an association between cognitive function and sleep duration. The emergence of up-to-date wearable sleep trackers allows researchers to investigate sleep duration without disturbing the patients’ sleep. OBJECTIVE This study investigated the association between sleep duration on the night before surgery and postoperative cognitive function using a wearable sleep tracker. METHODS In this 6-month prospective cohort study, we analyzed data from 194 patients aged ≥65 years who underwent elective non-cardiac and non-cranial surgery under general anesthesia. According to the sleep duration on the night before surgery, patients were categorized into following four groups: <5 h, 5–7 h, 7–9 h, and >9 h. Perioperative cognitive function and domains were assessed using a neuropsychological test battery, and the incidence and prevalence of POCD over 6 months after surgery were analyzed using the multiple logistic regression analysis. RESULTS During the 6-month follow-up period, 41 patients (21%) developed POCD. The incidence of POCD was significantly elevated for the patients with sleep duration less than 5 h (vs. 7–9 h; adjusted odds ratio, 2.67; 95% CI, 1.01–7.04; P <.05). The association between sleep duration and prevalence of POCD was limited to the early postoperative period (at 1 week and 1 month). Among the cognitive domains assessed, attentional function was significantly impaired in patients with a sleep duration of less than 5 h. [vs. 7–9 h at 1 week; 4/37 (10.8%) vs. 0/73 (0%); P <.05]. CONCLUSIONS Sleep duration less than 5 h on the night before surgery was significantly associated with worse attentional function after surgery and higher incidence of POCD. The present results indicate that sleep deprivation on the night before surgery may have a temporary but significantly negative influence on the patient’s postoperative cognitive function and is a potential target for preventing POCD. CLINICALTRIAL N/A