Effects of Caffeine Intake on Cognitive Performance Related to Total Sleep Deprivation and Time on Task: A Randomized Cross-Over Double-Blind Study

Abstract

Introduction

It is widely admitted that both total sleep deprivation (TSD) and extended task engagement (Time-On-Task, TOT) induce a cognitive fatigue state in healthy subjects. Even if EEG theta activity and adenosine both increase with cognitive fatigue, it remains unclear if these modifications are common mechanisms for both sustained attention and executive processes.

Methods

We performed a double-blind counter-balanced (placebo (PCBO) and caffeine (CAF) - 2×2.5 mg/kg/24 h)) study on 24 healthy subjects (33.7 ± 5.9 y). Subjects participated in an experimental protocol including an habituation/training day followed by a baseline day (D0 and D1) and a total sleep deprivation (TSD) day beginning on D1 at 23:00 until D2 at 21:00. Subjects performed the psychomotor vigilance test (PVT) assessing sustained attention, followed by the executive Go-NoGo inhibition task and the 2-NBack working memory task at 09:15 on D1 and D2.

Results

We showed differential contributions of TSD and TOT on deficits in sustained attention and both executive processes. An alleviating effect of caffeine intake is only observed on sustained attention deficits related to TSD and not at all on TOT effect. The caffeine dose slows down the triggering of sustained attention deficits related to TOT effect.

Discussion

These results suggest that sustained attention deficits induced by TSD rely on the adenosinergic mechanism whereas TOT effect observed for both sustained attention and executive would not.

Keywords:

• total sleep deprivation
• time on task
• caffeine
• sustained attention
• inhibition
• working memory
• cognitive fatigue
• mental fatigue
• healthy subjects

Abbreviations

BMI, body mass index; CAF, caffeine; EFs, executive functions; KSS, Karolinska sleepiness scale; PCBO, placebo; PSQI, Pittsburgh Sleep Quality Index; PVT, psychomotor vigilance test; ROI, region of interest; TSD, total sleep deprivation; TOT, time-on-task.

Clinical Trials Details

Clinical Trials Brief Title: Protocol PERCAF 2018. Clinical Trials Number: NCT03859882. Clinical Trials, First submission date: 25/02/2019.

Statement of Significance

It is widely admitted that total sleep deprivation (TSD) is responsible for a large range of cognitive deficits in healthy adults. However, the contribution of sleep debt per se, time on task and benefit of caffeine on cognitive deficits have received little investigation. Here we showed that the contribution of sleep debt per se, time on task and caffeine were not equivalent depending on the cognitive process engaged (ie, sustained attention versus executive processes). These results suggest that cognitive fatigue 1) would be differently supplied by sleep debt and time on task and 2) would not rely on the same neurophysiological changes according to the process involved. They would also open discussion upon concepts of cognitive fatigue and fatigability.

Data Sharing Statement

The authors do not intend to share individual data from de-identified participants, and no study documents will be made available.

Acknowledgments

The authors thank Philippe Colin, Benoît Lepetit, Cyprien Bourrilhon, Pierre Fabriès, Rodolphe Dorey and Bruno Schmid for their technical and logistic contribution to this work.

Disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Damien Léger reports grants from Sanofi, grants from Idorsia, grants from Jazz, grants from Bioserenity, outside the submitted work. The authors report no other potential conflicts of interest for this work.

Additional information

Funding

Financial supports were provided by the French General Directorate for Armament (Direction Générale de l’Armement), Department of Defense, Contract N°: PDH-1-SMO-2-509/SAN-1-509.