Pierre Philip, MD, PhD; Jacques Taillard, PhD; Nicholas Moore, MD, PhD; Sandrine Delord, PhD; Cédric Valtat, CRA; Patricia Sagaspe, PhD; Bernard Bioulac, MD, PhD
Acknowledgments: The authors thank Autoroutes du Sud de la France for allowing the use of their highways for the research, Nestlé for providing the coffee and decaffeinated coffee, GIE RE PSA (Groupement d'Intérêt Économique Recherche Peugeot Société Anonyme) Peugeot Citroën Renault for helping in the administrative coordination of the project, and T. Spector and C. Gilbert for managing the Groupe Opérationnel 3 (GO 3) (PREDIT [Programme de Recherche et d'Innovations dans les Transports Terrestres]).
Potential Financial Conflicts of Interest: None disclosed.
Requests for Single Reprints: Pierre Philip, MD, PhD, Clinique du Sommeil, CHU Pellegrin, Place Amélie Raba Léon, Unité Mixte de Recherche CNRS 5543, 33076 Bordeaux, Cedex, France; e-mail, firstname.lastname@example.org.
Current Author Addresses: Drs. Philip, Taillard, and Bioulac and Mr. Valtat: Clinique du Sommeil, CHU Pellegrin, Place Amélie Raba Léon, Unité Mixte de Recherche CNRS 5543, 33076 Bordeaux, Cedex, France.
Dr. Moore: Department of Pharmacology, Université Victor Segalen, INSERM U657, 33076 Bordeaux, Cedex, France.
Drs. Delord and Sagaspe: Laboratoire de Psychologie, Université Victor Segalen, 33076 Bordeaux, Cedex, France.
Author Contributions: Conception and design: P. Philip, J. Taillard, N. Moore, S. Delord, B. Bioulac.
Analysis and interpretation of the data: P. Philip, J. Taillard, N. Moore, S. Delord, C. Valtat, B. Bioulac.
Drafting of the article: P. Philip.
Critical revision of the article for important intellectual content: P. Philip, J. Taillard, N. Moore.
Final approval of the article: P. Philip, J. Taillard, N. Moore, S. Delord, C. Valtat, P. Sagaspe, B. Bioulac.
Provision of study materials or patients: P. Sagaspe.
Statistical expertise: P. Sagaspe.
Obtaining of funding: P. Philip, P. Sagaspe.
Administrative, technical, or logistic support: C. Valtat, P. Sagaspe.
Collection and assembly of data: P. Philip, J. Taillard, S. Delord, C. Valtat, B. Bioulac.
Sleep-related accidents often involve healthy young persons who are driving at night. Coffee and napping restore alertness, but no study has compared their effects on real nighttime driving performances.
To test the effects of 125 mL of coffee (half a cup) containing 200 mg of caffeine, placebo (decaffeinated coffee containing 15 mg of caffeine), or a 30-minute nap (at 1:00 a.m.) in a car on nighttime driving performance.
Double-blind, randomized, crossover study.
Sleep laboratory and open highway.
12 young men (mean age, 21.3 years [SD, 1.8]).
Self-rated fatigue and sleepiness, inappropriate line crossings from video recordings during highway driving, and polysomnographic recordings during the nap and subsequent sleep.
Participants drove 200 km (125 miles) between 6:00 p.m. and 7:30 p.m. (daytime reference condition) or between 2:00 a.m. and 3:30 a.m. (coffee, decaffeinated coffee, or nap condition). After intervention, participants returned to the laboratory to sleep.
Nighttime driving performance was similar to daytime performance (0 to 1 line crossing) for 75% of participants after coffee (0 or 1 line crossing), for 66% after the nap (P = 0.66 vs. coffee), and for only 13% after placebo (P = 0.041 vs. nap; P = 0.014 vs. coffee). The incidence rate ratios for having a line crossing after placebo were 3.7 (95% CI, 1.2 to 11.0; P = 0.001) compared with coffee and 2.9 (CI, 1.7 to 5.1; P = 0.021) compared with nap. A statistically significant interindividual variability was observed in response to sleep deprivation and countermeasures. Sleep latencies and efficiency during sleep after nighttime driving were similar in the 3 conditions.
Only 1 dose of coffee and 1 nap duration were tested. Effects may differ in other patient or age groups.
Drinking coffee or napping at night statistically significantly reduces driving impairment without altering subsequent sleep.
Philip P, Taillard J, Moore N, et al. The Effects of Coffee and Napping on Nighttime Highway Driving: A Randomized Trial. Ann Intern Med. 2006;144:785–791. doi: https://doi.org/10.7326/0003-4819-144-11-200606060-00004
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Published: Ann Intern Med. 2006;144(11):785-791.
Pulmonary/Critical Care, Sleep Disorders.
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