Caffeine Consumption, Sleep, and Affect in the Natural Environments of Depressed Youth and Healthy Controls*

Diana J. Whalen, BS; Jennifer S. Silk, PhD; Mara Semel, MS; Erika E. Forbes, PhD; Neal D. Ryan, MD; David A. Axelson, MD; Boris Birmaher, MD; Ronald E. Dahl, MD

Disclosures

J Pediatr Psychol. 2008;33(4):358-367. 

In This Article

Abstract and Introduction

Abstract

Objective: Sleep problems are a cardinal symptom of depression in children and adolescents and caffeine use is a prevalent and problematic issue in youth; yet little is known about caffeine use and its effects on sleep in youth with depression. We examined caffeine use and its relation to sleep and affect in youth's natural environments.
Methods: Thirty youth with major depressive disorder (MDD) and 23 control youth reported on caffeine use, sleep, and affect in their natural environment using ecological momentary assessment at baseline and over 8 weeks, while MDD youth received treatment.
Results: Youth with MDD reported more caffeine use and sleep problems relative to healthy youth. Youth with MDD reported more anxiety on days they consumed caffeine. Caffeine use among youth with MDD decreased across treatment, but sleep complaints remained elevated.
Conclusions: Findings suggest that both sleep quality and caffeine use are altered in pediatric depression; that caffeine use, but not sleep problems, improves with treatment; and that caffeine may exacerbate daily anxiety among youth with depression.

Introduction

Caffeine is the most widely consumed stimulant in the US and perhaps the world (Barone & Roberts, 1996). In adults, caffeine can affect arousal (Barry et al., 2005; Lyvers, Brooks, & Matica, 2004), attention (Lorist & Tops, 2003; Yeomans, Ripley, Davies, Rusted, & Rogers, 2002), reaction time (Childs & deWit, 2006; Kenemans & Lorist, 1995), and sleep (for a review, see Boutrel & Koob, 2004; Drapeau et al., 2006). Those same effects on youth, however, have received little empirical study (for a review, see Hughes & Hale, 1998). Work in this area is a crucial undertaking, given that many youth use caffeine daily and caffeine use is associated with poor sleep and daytime fatigue (National Sleep Foundation, 2006; Rapoport, Berg, Ismond, Zahn, & Neims, 1984; Rapoport, Elkins, Neims, Zahn, & Berg, 1981). Understanding caffeine's effects on sleep is particularly important in clinical disorders, such as depression, in which sleep difficulties are important features. The aim of the current study was to examine relationships between caffeine use and sleep in healthy and depressed youth using a natural approach to gather real-time information on how youth sleep and utilize caffeine in their daily lives.

Epidemiological work suggests that caffeine use in youth is worthy of empirical attention. 75–98% of youth consume at least one caffeinated beverage daily (Morgan, Stults, & Zabnick, 1982; National Sleep Foundation, 2006), with 31% reporting more than two per day (National Sleep Foundation, 2006). These rates approach the levels consumed by adults (Hughes & Oliveto, 1997). The subjective effects of high caffeine doses on youth are similar to those found in adults, such as nervousness and nausea (for a review, see Hughes & Hale, 1998). Behaviorally, caffeine use in youth has also been shown to improve performance on attention-related tasks. Children show improved performance and decreased self-reported "sluggishness" following moderate levels of caffeine consumption (Bernstein et al., 1994). On the other hand, when children who are regular caffeine users are asked to abstain, they report higher levels of negative affect (Goldstein & Wallace, 1997) and show decreased reaction times (Bernstein et al., 1998), suggesting those complex cycles of caffeine dependence can be set into motion even in childhood and adolescence.

Although less widely researched, caffeine may also play a cyclical role in affect regulation. Caffeine can contribute to arousal, anxiety, and irritability, thus exacerbating negative affect states (Brice & Smith, 2002; Childs & deWit, 2006; Smith, Sutherland, & Christopher, 2005). On the other hand, individuals may attempt to use caffeine as an affect regulator, much as they use other stimulants, such as cigarettes. Caffeine is a widely available, heavily marketed, and socially acceptable stimulant, even in child and adolescent populations. Caffeine may be particularly appealing to depressed youth seeking a "lift" due to fatigue or negative affect. In support of this speculation, self-reported anxious and depressive symptoms have been found to be elevated in adolescents with caffeine dependence (Bernstein et al., 1994; Bernstein, Carroll, Thuras, Cosgrove, & Roth, 2002). To address this question in our sample, we examined whether youth with depression used more caffeine than healthy controls and whether their caffeine use was associated with daily fluctuations in affect.

Caffeine use may have an important association with sleep quality. There is also evidence that, like adults (National Sleep Foundation, 2001), youth use caffeine to counteract daytime sleepiness. Caffeine use in youth tends to increase after Wednesday, peak on Saturday, and then decline (Pollack & Bright, 2003). In fact, adolescents who drank two or more caffeinated beverages a day were more likely to report an insufficient amount of sleep on school nights, a self-described sleep disturbance, and problems related to drowsiness, than those who drank one or less (National Sleep Foundation, 2006). In addition, children who were heavy caffeine users reported an increase in sleep disruption following a day of caffeine consumption (Pollack & Bright, 2003). This finding demonstrates the potential for caffeine consumption to contribute to cycles of sleep disruption in youth.

The second focus of our study was on youth's sleep behaviors in the natural context. Youth with major depressive disorder (MDD) frequently complain of sleep disturbances, regardless of caffeine use (Bertocci et al., 2005; Ryan et al., 1987). A large body of literature implicates sleep dysregulation in adult depression, with several studies suggesting that sleep difficulties precede the onset of depressive disorders (for a review, see Riemann & Voderholzer, 2003). Sleep complaints are extremely common in children and adolescents with MDD, with as many as 90% reporting significant sleep problems (Ryan et al., 1987). Reported sleep problems have included hypersomnia, nighttime awakenings, daytime sleepiness, and circadian reversal (Dahl et al., 1996). In a previous study, our group found that children and adolescents with depression, compared to controls, reported significantly worse subjective sleep in terms of sleep quality, number of awakenings, minutes awake, and ease of waking (Bertocci et al., 2005). The current study extends this work by examining group differences in subjective sleep behaviors in the natural environments of healthy and depressed youth over several months, as well as how these sleep behaviors are related to caffeine consumption.

A final, more exploratory goal was to examine whether subjective sleep and caffeine use change across the course of treatment for youth with depression. Although caffeine consumption is not specifically targeted in treatments for depression, it may change as participants stabilize and normalize their affect states and daily activities as a function of treatment via medication or psychosocial therapy. Alternatively, more specific treatments (or adjunctive treatment) addressing these behaviors may need to be developed. To the extent that sleep and caffeine behaviors are altered in pediatric depression, it will be important to understand whether standard treatments for these disorders impact these behaviors. This study represents a preliminary step toward addressing this question.

To address these questions, we utilized Ecological Momentary Assessment (EMA) to objectively measure affect, behavior, and caffeine use in the home environment. EMA is an ecologically valid method of gathering representative real-time data on affect and behavior in natural environments through the use of signaling devices (Axelson et al., 2003; Larson, Csikszentmihalyi, & Graef, 1980; Shiffman et al., 2006; Silk, Steinberg, & Morris, 2003). EMA can provide more accurate and objective data on day-to-day shifts in caffeine consumption and sleep, but has not been applied to examining these behaviors in youth with depression. In fact, most studies have relied on retrospective reports of caffeine intake and sleep habits—methods limited by memory biases.

In summary, this study builds on previous research to address four questions: (a) Do youth with depression use more caffeine in their daily lives than healthy youth?; (b) Do youth with depression report poorer sleep in their daily lives than healthy youth?; (c) How is daily caffeine use related to sleep and affect?; and (d) Do sleep and caffeine use change as youth with MDD go through treatment? We hypothesized that youth with MDD would report greater caffeine use and subjective sleep problems than healthy youth, that caffeine use would be associated with greater sleep problems that night and greater negative affect that day, especially for youth with MDD, and that both sleep and caffeine use would improve throughout treatment.

*A portion of this data was presented at the Society for Research in Child Development Biennial Meeting, March–April 2007, Boston, MA, USA.

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