Revving Up and Staying Up: Energy Drink Use Associated with Anxiety and Sleep Quality in a College Sample

Abstract

Associations among caffeinated energy drink use, anxiety, and sleep quality were examined in a young adult sample (N = 107). A 7-day retrospective survey methodology was used to assess consumption rates among college student athletes, ROTC cadets, and those in a control group. Regression analyses revealed that energy drink use explained 29% of the variance in anxiety scores and 20% in sleep disturbance scores. Greater frequency of energy drink use was associated with poorer sleep quality, longer sleep latency, shorter sleep duration, and lower habitual sleep efficiency. No group differences in energy drink consumption were revealed. More research into the effects of energy drink use on psychological adjustment variables appears warranted. Keywords: energy drinks; caffeine; anxiety; sleep quality; college students ********** Energy drink use appears to be ubiquitous, particularly among young adults, who may expect these products to improve concentration and performance, combat fatigue, or even to counteract the effects of alcohol intoxication. Data examining the prevalence and pattern of energy drink consumption, as well as the potential risks, have emerged (Malinauskas, Aeby, Overton, Carpenter-Aeby, & Barber-Heidal, 2007; Oteri, Caputi, & Calapai, 2007; Miller, 2008). For example, recent survey data from 602 college students found that frequency of energy drink use was positively related to marijuana use, sexual and other risk-taking, fighting, and failure to wear a seatbelt (Miller, 2008). Few studies have examined relationships among energy drink use and psychological adjustment variables, such as anxiety and sleep quality. A secondary goal was to examine use frequencies in certain subgroups--athletes and ROTC cadets--who regularly participate in physically demanding co-curricula activities. Caffeine, Anxiety, and Sleep While energy drinks often contain ingredients such as taurine, glucose, carbohydrates, herbal extracts, and B vitamins, caffeine has been the most studied in relation to anxiety and sleep. A central nervous system (CNS) and cardiac stimulant, caffeine acts as an antagonist to adenosine, a substance that has been shown to promote sleep and to influence autonomic nervous system arousal (Alsene, Deckert, Sand, & de Wit, 2003; Roehrs & Roth, 2008). Moderate doses of 75 to 200 mg improve attention, alertness, and visual vigilance, reduce fatigue and shorten reaction times, and improve subjective mood states (Childs & de Wit, 2008; Herz, 1999; Lieberman, Tharion, Shukitt-Hale, Speckman, & Tulley, 2002; Smith, 2002). Habitual caffeine use, however, may moderate these effects (Hamleers, et al., 2000). Caffeine may also exacerbate pre-existing cardiac conditions and have side effects such as increased heart rate and palpitations, elevated blood pressure, and restlessness. Consumption of caffeine in higher quantities prompts anxiety-related responses. Veleber and Templer (1984) found that 65% participants who received a 300 mg dose of caffeine showed significant increases in anxiety scores from pre- to post-test controlling for weight and daily caffeine use. Telch, Silverman, and Schmidt (1996) reported that 400 mg or more of caffeine increases autonomic nervous system arousal, respiration rate, oxygen intake, and carbon dioxide elimination, as well as prompts negative somatic sensations, such as shaking and trembling. However, Smith (2002) has questioned the ecological validity of such studies based on evidence that caffeine users do not typically ingest large amounts of caffeine all at once, but rather self-regulate their intake throughout the day to avoid negative side effects and sleep disturbances. Laboratory data has demonstrated links between caffeine use and sleep. Studies utilizing polysomnography have generally shown that caffeine prior to bedtime may increase sleep onset latency, decrease total sleep time, lower sleep efficiency, and reduce slow-wave sleep (Paterson, Nutt, Ivarsson, Hutson, & Wilson, 2009; Landolt, Werth, Borbely, & Dijk, 1995). …