by Bianca Garilli, ND
Sleep plays an important role in foundational health with inadequate amounts contributing to risks associated with obesity, type 2 diabetes (T2D), metabolic syndrome, hypertension and cardiovascular disease.1 One study reviewing the relationship between insufficient sleep and chronic health issues concluded, “Sleep duration of less than 6 hours is a risky behavior for the development of chronic diseases, particularly stroke and cancer, and should be therefore addressed in public health campaigns.”2
Studies have shown that the risk of developing T2D increases with short duration of sleep (≤5–6 h/night), long duration of sleep (>8–9 h/night), difficulty initiating sleep and difficulty maintaining sleep.3 Quantity and quality of sleep consistently and significantly predict the risk of the T2D development although the mechanisms underlying this relationship are not clear and, in fact, may differ between short and long sleepers.3
Recently, it has been hypothesized that one possible mechanism connecting inadequate sleep and T2D may involve the adipocyte-derived hormone, leptin. Leptin plays a key role in the regulation of energy balance, appetite and body weight through a negative feedback signaling pathway.4 Many studies have shown that lower leptin levels are associated with shorter sleep duration in non-obese individuals while in individuals with obesity, leptin levels and sleep duration resulted in a non-significant U shaped association.1
A recent study aimed to learn more about this relationship. Researchers from Osaka City University Graduate School of Medicine in Osaka, Japan hypothesized that dysregulation of circulating leptin might be associated with poor sleep quality in obese T2D patients independent of sleep apnea. To test this premise, a cross-sectional study was conducted between October 2011 and July 2016 with 182 T2D patients. 100 of the subjects were male and 82 female; 113 of the total participants were diagnosed with obesity (body mass index >25 kg/m2).1 An overnight sleep study recorded by an EEG was measured along with respiratory flow pressure, oxygen saturation and heart rate. Additionally, nocturnal and ambulatory blood pressure was recorded along with various biomarkers such as leptin levels, eGFR, HbA1c, fasting glucose, triglycerides, HDL and LDL cholesterol.1
Results from this study indicate a favorable relationship existed between leptin and sleep quality in participants with T2D and obesity; this association was not observed in the non-obese participants with T2D. In those T2D patients with obesity, a positive correlation was seen between plasma leptin levels and deep sleep assessed by delta power, but not for total sleep duration. These results were independent of age, BMI and a sleep apnea index. The findings of this study are interesting but require further research to understand their significance (especially given that leptin was not associated with total sleep time) and translation to clinical recommendations.1
Why is this Clinically Relevant?
- Leptin levels signal fullness and satiety
- Rising leptin levels together with increasing obesity may indicate development of leptin-resistance
- Insufficient sleep is associated with various cardiometabolic disease processes including T2D
- Leptin levels and sleep quality were found to be correlated in T2D individuals with obesity but not in individuals with T2D without obesity
- Further studies are needed to understand the role leptin plays in the obesity-sleep quality relationship
- Hirota T, Morioka T, Yoda K, et al. Positive association of plasma leptin with sleep quality in obese type 2 diabetes patients. J Diabetes Investig. 2018;doi:10.1111/jdi.12826. (Epub ahead of print).
- Von Ruesten A, Weikert C, Fietze I, Boeing H. Association of sleep duration with chronic diseases in the European prospective investigation into cancer and nutrition (EPIC)-potsdam study. PLoS ONE. 2012;7(1):e30972.
- Cappuccio FP, D’Elia L, Strazzullo P, Miller MA. Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes Care. 2010;33(2):414-420.
- Harris RB. Direct and indirect effects of leptin on adipocyte metabolism. Biochim Biophys Acta. 2014;1842(3):414-423.