The effect of slow-wave sleep and rapid eye-movement sleep interventions on glycaemic control: a systematic review and meta-analysis of randomised controlled trials.

Poor glycaemic control is found in diabetes, one of the most common, serious, non-communicable diseases worldwide. Trials suggest a relationship between glycaemic control and measures of sleep including duration and quality of sleep. Currently, the relationship between specific sleep stages (including slow-wave sleep (SWS), a sleep stage mainly found early in the night and linked to restorative functioning) and glycaemic control remains unclear. This systematic review aimed to synthesise the evidence of the effectiveness of specific sleep stage manipulation on measures of glycaemic control (insulin resistance, fasting and post-prandial glucose and insulin). Public databases (eg psychINFO, MEDLINE, Academic Search Complete, psychARTICLES, OpenDissertations, Scopus and Cochrane library) were searched for randomised controlled trials. Trials were included if they involved direct manipulation of SWS and/or rapid eye-movement sleep to explore the impact on measures of glycaemic control (insulin resistance, fasting and post-prandial glucose and insulin). Eight trials met the eligibility criteria, with four providing data for inclusion in one of the three meta-analyses. Insulin resistance was significantly higher in the SWS disruption when compared to the normal sleep condition, (p = 0.02). No significant differences were found for measures of fasting or post-prandial glucose or insulin. Risk of bias was considered low for performance bias, detection bias and incomplete outcome data, with unclear selection bias. This is an emerging area of research and this review provides preliminary findings and recommendations for future research around optimising sleep stage disruption (to further explore mechanisms) and sleep stage enhancement techniques (to explore potential interventions).