Caffeine may disrupt the impact of real-time drowsiness on cognitive performance: a double-blind, placebo-controlled small-sample study

E Aidman,K Johnson,S Banks,J Fidock,C Della Vedova,G M Paech,C Yates,S Jackson,M Pajcin,G H Kamimori,M Balin,E Mitchelson

doi:10.1038/s41598-021-83504-6

Abstract

Caffeine is widely used to promote alertness and cognitive performance under challenging conditions, such as sleep loss. Non-digestive modes of delivery typically reduce variability of its effect. In a placebo-controlled, 50-h total sleep deprivation (TSD) protocol we administered four 200 mg doses of caffeine-infused chewing-gum during night-time circadian trough and monitored participants' drowsiness during task performance with infra-red oculography. In addition to the expected reduction of sleepiness, caffeine was found to disrupt its degrading impact on performance errors in tasks ranging from standard cognitive tests to simulated driving. Real-time drowsiness data showed that caffeine produced only a modest reduction in sleepiness (compared to our placebo group) but substantial performance gains in vigilance and procedural decisions, that were largely independent of the actual alertness dynamics achieved. The magnitude of this disrupting effect was greater for more complex cognitive tasks.

Highlights

Caffeine is widely used to promote alertness and cognitive performance under challenging conditions, such as sleep loss
Prior to undergoing total sleep deprivation (TSD), participants were given a 10 h baseline sleep opportunity with no differences observed in total sleep time between placebo (8.7 ± 0.49 h) and caffeine (8.9 ± 0.52 h) groups
The observed dissociation in our caffeine group between cognitive test performance and objectively measured drowsiness immediately prior to performing the test, replicates the dissociation pattern previously reported for simulated driving[13]

Summary

Introduction

Caffeine is widely used to promote alertness and cognitive performance under challenging conditions, such as sleep loss. Real-time drowsiness data showed that caffeine produced only a modest reduction in sleepiness (compared to our placebo group) but substantial performance gains in vigilance and procedural decisions, that were largely independent of the actual alertness dynamics achieved The magnitude of this disrupting effect was greater for more complex cognitive tasks. We have previously found that caffeine administered via chewing gum and strategically timed to circadian trough periods during sleep deprivation, was able to reduce subjective fatigue, mental exhaustion and irritability[14] and rescue the declining performance on a simulated driving task[15] It improved performance on standard tests of vigilance and working memory[16] while having no substantial impact on the recovery sleep[17], glucose metabolism and feelings of hunger[14]. Individual JDS scores averaged over the 5-min window immediately preceding the cognitive testing, formed the drowsiness predictor of cognitive performance

Methods

Results

Conclusion