Sleep deprivation elevates circulating creatine levels in healthy adults: a pilot study

Abstract

This pilot study investigated the impact of a 24-h sleep deprivation period on circulating biomarkers of creatine metabolism in 23 healthy adults (24.6 ± 4.3 years; 7 females). Contrary to the hypothesis that sleep deprivation would reduce creatine levels, serum creatine significantly increased post-deprivation (95% CI −3.66 to 25.22 μmol/L; P = 0.03), while guanidinoacetic acid and creatinine levels remained unchanged. Our findings suggest a complex relationship between sleep deprivation and creatine metabolism, emphasizing the need for further research using advanced biomarkers to elucidate these mechanisms and assess creatine’s potential protective role under stress conditions.

Introduction

Creatine, a natural non-proteinogenic amino acid derivative, plays a central role in maintaining optimal bioenergetics throughout the human body. It is primarily utilized for the rapid synthesis of adenosine triphosphate (ATP), the essential cellular energy currency, particularly under conditions of elevated energy demands [1]. Reduced creatine availability is a hallmark of various physiological and pathological states [2], often reflecting heightened utilization of this energy-supporting compound in energy-intensive organs such as the brain. Notably, diminished creatine levels have been observed in neurodegenerative and neurodevelopmental disorders, brain tumors, traumatic brain injuries (for an extensive review, see Ref. [3]), as well as following an acute video gaming session [4] or period of food abstention [5]. Sleep deprivation, preliminarily recognized as a hypo-energetic condition [6], may similarly affect creatine dynamics. However, whether a single session of sleep deprivation compromises creatine levels remains unexplored. This pilot study hypothesized that a 24-h period of sleep deprivation would reduce circulating creatine levels in healthy adults.

Methods

Twenty-three young, healthy adults (mean age: 24.6 ± 4.3 years; 7 females) provided informed consent to participate in this observational before-and-after pilot study. The study was approved by the local IRB at the University of Novi Sad (Approval No. 9-09-14/2023-2B) and conducted in accordance with the principles outlined in the Declaration of Helsinki. Participants were non-vegetarians, free from acute or chronic health conditions, and had abstained from creatine-containing dietary supplements for at least four weeks prior to the study. The study involved a single 24-h sleep deprivation session conducted in a controlled sleep quarantine room within the laboratory. Participants were continuously monitored by research staff to ensure wakefulness, particularly during nighttime hours. Physical activity was not systematically monitored during the sleep deprivation session. However, all participants were instructed to limit their activity to essential daily functions, such as eating, voiding, and other basic physiological needs. This restriction aimed to minimize potential variability in energy expenditure and physical exertion, thereby reducing their potential influence on the study outcomes. Participants adhered to their regular dietary patterns throughout the session. To ensure dietary consistency and eliminate potential confounding effects of creatine intake, they were provided with two standardized meals that did not contain creatine. These meals collectively contributed a total caloric intake of 750 kcal, helping to maintain controlled nutritional conditions during the study. All participants refrained from food intake for at least 12 h before blood sampling, although ad libitum water consumption was permitted. Fasting blood samples were collected from the antecubital vein at baseline and 24 h post-sleep deprivation. Serum levels of creatine, guanidinoacetic acid (GAA, a direct precursor of creatine), and creatinine (an end-product of non-enzymatic creatine conversion) were quantified using modified liquid chromatography-tandem mass spectrometry as previously described [7]. The normality of the data distribution was assessed using the Shapiro–Wilk test. Within-group differences during the trial were analyzed using t-tests for data that met the assumption of normality. A significance threshold of P ≤ 0.05 was applied to all statistical tests. Missing data were excluded from the analyses. All statistical procedures were performed using SPSS version 24.0 for Mac (IBM SPSS Statistics, Chicago, IL, USA).

Results

The final study cohort comprised 22 participants, as one female participant (aged 22 years) failed to complete the sleep deprivation protocol and the subsequent blood sampling. Unexpectedly, serum creatine levels showed a significant increase from baseline to post-sleep deprivation (P = 0.03), with the 95% confidence interval (CI) for the mean change ranging from −3.66 to 25.22 μmol/L. A similar, though non-significant, trend was observed for elevated serum guanidinoacetic acid (GAA) levels following sleep deprivation (P = 0.09), while serum creatinine levels remained largely unchanged (P = 0.42) (Fig. 1).

Fig. 1.

Box plots illustrating serum indices of creatine metabolism before (gray column) and after a 24-h sleep deprivation period (orange column) (n = 22). An asterisk (*) denotes statistical significance at P < 0.05 for baseline versus follow-up comparisons, as determined by a paired t-test

Discussion

This study is, to our knowledge, the first to evaluate the effects of a 24-h sleep deprivation period on circulating biomarkers of creatine metabolism in healthy adults. Contrary to our initial hypothesis, sleep deprivation significantly increased serum creatine levels at the 24-h follow-up, while other biomarkers remained unaffected. The underlying mechanism for this unexpected phenomenon remains unclear. Elevated circulating creatine levels may result from one or more of the following: (1) enhanced endogenous creatine synthesis, particularly in extracerebral tissues (such as the liver, kidney or pancreas), to sustain energy-intensive neuronal activity during prolonged wakefulness; (2) reduced clearance of creatine via renal or extrarenal pathways; (3) diminished cerebral uptake of creatine, potentially due to sleep deprivation-induced alterations in the blood–brain barrier; (4) increased efflux of brain-derived creatine into the circulation; (5) a combination of these mechanisms; or (6) an as-yet unidentified mechanism. Further investigations, employing advanced biomarkers of creatine turnover such as isotopic tracers (e.g., guanidino-[¹³C₂]acetic acid), are warranted to monitor creatine dynamics in target tissues and excretory pathways (including urine) during both acute and chronic sleep deprivation episodes. Future research should encompass both clinical and non-clinical populations exposed to high-stress conditions to comprehensively examine the relationship between elevated creatine availability and cognitive or neurological performance (including brain EEG or functional MRI) in this context. Additionally, studies should investigate potential moderating factors, including sex differences, physical activity, variations in muscle mass, chronotype, and habitual sleep duration, as these variables may influence the extent to which creatine availability affects brain function. Future research should incorporate additional fundamental biochemical blood markers, including blood glucose levels, cholesterol, and free fatty acids, alongside creatine. The inclusion of these parameters would provide a more comprehensive assessment of the biochemical profile and contribute to a more robust and reliable evaluation of the study outcomes. A nuanced understanding of all above interactions could provide valuable insights into personalized supplementation strategies and their potential cognitive and neuroprotective benefits. Interestingly, exogenous creatine supplementation has been shown to enhance brain creatine levels (also cognitive performance) in sleep-deprived individuals [8, 9], suggesting a potential protective role of creatine. However, it remains uncertain whether these effects are restricted to individuals with low baseline creatine availability.

Author contributions

Conceptualization: NT, SMO; Funding: SMO; Methodology: all authors; Formal analysis: all authors; Supervision: DN, SMO; Writing—original draft: NT, SMO; Editing: all authors.

Funding

This study was partially funded by the Serbian Ministry of Science, Technological Development and Innovation.

Declarations

Conflict of interest

All authors declare there are no competing interests.

Ethical approval

The ethical approval was granted by the local IRB at the University of Novi Sad (# 9-09-14/2023-2B).

Consent to participate

Written informed consent was obtained from all respondents to participate in the study. The research was conducted ethically following the World Medical Association Declaration of Helsinki.