The Effect of Caffeine and Sleep Quality on Military Pilot Students’ Flight Performance-Related Cognitive Function

ABSTRACT

Objective

To assess the effect of caffeine and sleep quality on the flight performance-related cognitive function.

Background

High levels of cognitive performance in pilots is required for flight safety.

Methods

Students at a military flight school in Thailand were invited to participate in this study. Exclusion criteria was positive screening for caffeine use disorder. We examined three cognitive functions required for flight performance: (1) vigilance (Mackworth Clock Test), (2) situational awareness, including memory (Corsi block-tapping test) and spatial reasoning (mental rotation test), and (3) reaction time (Deary-Liewald task). Neuropsychological tasks were performed before and 30 minutes after drinking a bottle of 220 ml coffee containing 143 mg of caffeine. Sleep quality was measured by the Thai-Pittsburgh Sleep Quality Index.

Results

Twenty-nine healthy males without caffeine use disorder with a mean age of 25.1 years were enrolled. After low-dose caffeine intake (<3 mg/kg body weight), cognitive performance improved significantly in vigilance, situation awareness, and reaction time. Baseline cognitive performance was not different between high (HSQ) and low sleep quality (LSQ) groups. After drinking coffee, however, participants with HSQ demonstrated improvements in vigilance and reaction time, while the LSQ group had improved vigilance only.

Conclusion

Low dose caffeine improved vigilance, situational awareness, and reaction time which were cognitive functions required for flight performance. The cognitive-enhancing effect of caffeine was more obvious in student pilots with high-quality sleep.

Acknowledgments

The authors thank Air vice-marshal Waipote Kerngphark, Commandant, Flying Training School of the Royal Thai Air Force (RTAF), who granted us permission and offered help during data collection. We also thank Group Captain Phithak Onsiri, flight surgeon and psychiatrist, who reviewed and provided insightful suggestion about the cognitive experiments. We appreciate Professor Gijsbert Stoet for his permission to use PsyToolkit in the experiment. We thank Naratip Sa-nguanpanich for her help with statistical analysis. We also thank Dr. Mark Simmerman, PhD, for his insightful advice and English writing. We are grateful to all participants for their interest and time.

Disclosure Statement

The authors have no relevant conflicts of interest to declare.

Ethics Committee Approval

This study was approved by Institutional Review Board, Faculty of Medicine Siriraj Hospital, Mahidol University on 20 March 2020; Certificate of Approval (CoA) number Si 231/2020.

Supplementary Material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This study was supported by the Siriraj Research and Development Fund (Grant Number R016331052) and the Thai Neuropsychiatry Development Fund, Siriraj Foundation. The corresponding author was supported by the Chalermphrakiat Grant, Faculty of Medicine Siriraj Hospital, Mahidol University.