Effects of dietary caffeine on mood when rested and sleep restricted

Abstract

Prolonged use of caffeine can lead to physical dependence evidenced by characteristic withdrawal symptoms during abstinence. Debate exists as to whether mood enhancement by caffeine represents a net effect or merely the restoration of abstinence-induced mood decrements. One aim of this study was to determine the net effects on mood of dietary caffeine compared with prolonged abstinence. In addition, the study aimed to determine whether caffeine restores mood degraded by a non-caffeine source, namely, sleep restriction. A double-blind placebo-controlled cross-over design was employed in which 48 male and female volunteers alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while being either rested or sleep restricted. Mood was assessed using a computerized version of the profile of mood states (POMS), giving scores for overall mood and six mood dimensions. Gender had small effects on mood, whereas all mood dimensions were markedly adversely affected by sleep restriction. Caffeine had no significant net enhancing effects on mood when participants were rested, and produced no net restorative effects when mood was degraded by sleep restriction. On the contrary, caffeine-induced decrements in mood were observed during both conditions of rest and sleep restriction.

Dietary Caffeine, Performance and Mood: Enhancing and Restorative Effects after Controlling for Withdrawal Reversal

“…The overall results are consistent in all important respects with the withdrawal reversal hypothesis, and are supported by other recent studies showing enhancing effects only in persons who are caffeine deprived [e.g. 7,11,[18][19][20][21][22] . That is, a substantial body of evidence now exists indicating that improvements in human performance and mood, long held to be primary effects of dietary caffeine, are more readily attributable to reversal of the withdrawal effects that accompany brief abstinence.…”

Effects of Alcohol, Coffee, and Tobacco, Alone or in Combination, on Physiological Parameters and Anxiety in a Young Population

“…15 Caffeine has been associated with increases in several cardiovascular disease risk factors, 16,17 such as higher blood pressure (BP), an acute effect of coffee. 18 In contrast, recent studies have reported health benefits associated with coffee consumption. 19,20 At low doses, caffeine improves hedonic tone and reduces anxiety, while it produces an increase in tense arousal, including anxiety, nervousness, and jitteriness, at high doses.…”

Caffeine and theanine exert opposite effects on attention under emotional arousal

“…Caffeine enhances physiological arousal, by activating both the sympathetic nervous system by increasing heart rate and blood pressure (Davidson and Smith 1991;Green and Suls 1996;James and Gregg 2004) and the hypothalamic pituitary adrenal axis by increasing cortisol (Lovallo et al 1996(Lovallo et al , 2005. Caffeine exerts physiological effects similar to those of acute stress (Gerra et al 2001;Kudielka et al 2004) and may augment the physiological stress response (Lovallo et al 2006).…”