Credit: xiaphias/Wikipedia This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2015 Phys.org Common biomarkers of sleep debt found in humans, rats, study finds (Phys.org)—Ideally, we would get the appropriate amount of sleep to keep our bodies healthy, but in our modern society things like jet lag, extended work hours, or using electronic devices cause disruptions in our sleep/wake cycle often leading to fewer hours of quality sleep. Most people suffer from chronic sleep restriction rather than complete deprivation, but there are very few studies that explore the effects of sleep restriction. Amita Sahgal and Aalim Weljie from the University of Pennsylvania and Peter Meerlo, from the University of Groningen in The Netherlands, investigated at how chronic sleep restriction affects the body’s metabolic processes. Their work is published in the Proceedings of the National Academy of Sciences. More information: “Oxalic acid and diacylglycerol 36:3 are cross-species markers of sleep debt.” PNAS 2015 ; published ahead of print February 9, 2015www.pnas.org/content/early/2015/02/03/1417432112AbstractSleep is an essential biological process that is thought to have a critical role in metabolic regulation. In humans, reduced sleep duration has been associated with risk for metabolic disorders, including weight gain, diabetes, obesity, and cardiovascular disease. However, our understanding of the molecular mechanisms underlying effects of sleep loss is only in its nascent stages. In this study we used rat and human models to simulate modern-day conditions of restricted sleep and addressed cross-species consequences via comprehensive metabolite profiling. Serum from sleep-restricted rats was analyzed using polar and nonpolar methods in two independent datasets (n = 10 per study, 3,380 measured features, 407 identified). A total of 38 features were changed across independent experiments, with the majority classified as lipids (18 from 28 identified). In a parallel human study, 92 metabolites were identified as potentially significant, with the majority also classified as lipids (32 of 37 identified). Intriguingly, two metabolites, oxalic acid and diacylglycerol 36:3, were robustly and quantitatively reduced in both species following sleep restriction, and recovered to near baseline levels after sleep restriction (P < 0.05, false-discovery rate < 0.2). Elevated phospholipids were also noted after sleep restriction in both species, as well as metabolites associated with an oxidizing environment. In addition, polar metabolites reflective of neurotransmitters, vitamin B3, and gut metabolism were elevated in sleep-restricted humans. These results are consistent with induction of peroxisome proliferator-activated receptors and disruptions of the circadian clock. The findings provide a potential link between known pathologies of reduced sleep duration and metabolic dysfunction, and potential biomarkers for sleep loss.