Abstract

Time of Day Variation in the Human Metabolic Profile and Effect of Sleep Deprivation

Sarah Davies, PostDoc Fellow, University of Surrey

Targeted liquid chromatography-mass spectrometry (LC-MS) metabolomics has been employed to examine the effect of time of day variation and total sleep deprivation on plasma metabolite rhythms. Twelve healthy young males remained in controlled laboratory conditions with respect to light, sleep, meals and posture during a 24 h wake/sleep cycle followed by 24 h of wakefulness. Two-hourly plasma samples collected over the 48 hour period were analysed using the MetaDisIDQ targeted metabolomics kit (Biocrates Life Sciences AG, Innsbruck, Austria). The concentrations of 171 metabolites were measured in each sample. Principal Component Analysis revealed a clear time of day variation both during the wake/sleep cycle and during 24 h of wakefulness. Daily rhythms were observed in the majority of metabolites (64%), mostly with higher levels during the day (87%). Most metabolites (72%) maintained their rhythmicity during 24 h of wakefulness, but with reduced amplitude (85%). Fewer metabolites (23%), mainly lipids and acylcarnitines, were affected by sleep deprivation, all having significantly increased levels during sleep deprivation compared with during sleep. Defining time of day and circadian variation in the human metabolome as well as the effect of light, food and sleep on metabolite rhythms will provide an important baseline for future metabolomic studies.