Energy Drink Consumption and Its Association With Sleep Problems Among U.S. Service Members on a Combat Deployment

Afghanistan, 2010

Robin L. Toblin, PhD; Kristina Clarke-Walper, MPH; Brian C. Kok; Maurice L. Sipos, PhD; Jeffrey L. Thomas, PhD


Morbidity and Mortality Weekly Report. 2012;61(44):895-898. 

In This Article

Editorial Note

Military and civilian findings show that more than half of adolescents and young adults drink at least one energy drink per month,[5] with approximately 6% consuming energy drinks daily.[2,3] In this study, 45% of service members reported consuming one or more energy drinks per day, a considerably higher prevalence. This might reflect the unique and extreme demands of a combat deployment and the widespread availability of energy drinks in the combat environment (e.g., free distribution in dining facilities and available for purchase in convenience stores). No differences in energy drink consumption by age or rank were observed, demonstrating the ubiquitous nature of energy drink consumption during deployment.

Consumption of three or more energy drinks per day was associated with negative sleep outcomes that included sleepiness on the job and sleeping ≤4 hours per night. This is a low number of hours of sleep even in the deployed environment, in which half of respondents averaged ≤5 hours of sleep. Although causality could not be ascertained from this cross-sectional study, this relationship is consistent with civilian studies demonstrating that caffeine use contributes to daytime sleepiness[6] and sleep problems,[1,6] and that inadequate sleep and daytime sleepiness can impair work productivity.[7] Further, this study suggests that high levels of energy drink consumption might indirectly impair performance in a military setting. Service members who consumed three or more energy drinks per day reported significantly greater sleep disruption because of combat stress, personal issues, and illness, but not because of external factors. This is similar to results found in a civilian study in which caffeine use caused an increase in nocturnal worry and sleeplessness[8] and a military study that found that mental health symptoms increased energy drink use.[9] Because inadequate sleep can considerably influence a person's health, excessive energy drink consumption might indirectly contribute to poor health.

The findings in this report are subject to at least five limitations. First, cause and effect cannot be determined because the data are cross-sectional. It is unclear whether service members with sleep problems used more energy drinks to stay alert, or if heavy use of energy drinks led to sleep disruptions; published studies suggest a cyclical combination of both.[1,5] Second, the survey did not allow for a true estimate of caffeine intake. The caffeine content in energy drinks varies by the size of the can and milligrams of caffeine per ounce.[1] Leading brands contain 80–160 mg of caffeine in their smallest containers, similar to 1–2 cups of coffee, with some brands containing up to 500 mg.[1] In addition, the survey did not measure consumption of other caffeinated beverages (e.g., coffee, soft drinks, or tea). Third, the phrasing of the question about average number of energy drinks consumed per day might have resulted in an underestimate of energy drink use; a person who consumed several drinks a week, but did not consume them daily, might have answered zero to that question. Fourth, this study did not control for variables that might have confounded the relationship between energy drink consumption and sleep outcomes (e.g., mental health problems, physical injury, amount of time deployed, or peer group/unit effects). Nonetheless, survey data from questions about stress, illness, personal life, and leisure activities as reasons for sleep disruption might serve as proxies for those variables not analyzed. Finally, analyses did not control for sleep medication use, which also can cause daytime sleepiness. However, although groups differed in overall sleep outcomes, the groups did not differ in their prevalence of sleep medication use (approximately one in seven), suggesting that the main associations were not explained by use of sleep medication.

The widespread use of energy drinks across demographics and its association at high doses with sleep problems and work impairment, coupled with known associations between caffeine and sleep problems and sleepiness in the general population,[1,6,7] support the need to educate service members about moderating consumption of energy drinks. Service members who used energy drinks in moderation (i.e., one or two per day) had similar levels of sleep problems and performance as those who did not use energy drinks. Based on the caffeine content of leading brands of energy drinks, this dosage is equivalent to the average caffeine consumption by men ages 20–29 years in the United States[10] and has been associated with cognitive performance (e.g., visual vigilance, reaction time, and alertness).[1,4] This also might explain the lack of a clear dose-response relationship between energy drink consumption and sleep problems.

The marketing of these types of drinks as energy boosters, together with their availability in the combat environment, makes it easy for service members to consume them in large volumes. Energy drinks are relatively new, generally unregulated, and lack warning labels. Service members should be educated that the long-term health effects of energy drink use are unknown, that consuming high doses of energy drinks might affect mission performance and sleep, and that, if used, energy drinks should be consumed in moderation.