Keane Michael A, James Jack E
School of Psychology, National University of Ireland, Galway, Ireland.
Hum Psychopharmacol. 2008 Dec;23(8):669-80. doi: 10.1002/hup.987.
Until recently, little account had been taken of the confounding effects of caffeine withdrawal and withdrawal reversal when examining the net effects of dietary caffeine.
By including a manipulation involving sleep restriction, the present study aimed to extend recent findings from research in which caffeine withdrawal and withdrawal reversal were controlled. The main aims of the study were to examine the net effects of caffeine, as well as its potential restorative effects following sleep restriction, on EEG, performance and mood.
A randomised cross-over design was used in which 15 participants alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for four consecutive weeks following either usual sleep or sleep restriction. EEG activity was measured at 32 sites during eyes closed, eyes open and performance of a vigilance task.
Modest effects of caffeine were found in the delta and beta bandwidths, but no main effects of caffeine were observed in the theta or alpha bandwidths. Overall, the effects of caffeine on EEG activity were relatively few, weak and inconsistent, and no evidence was found of net restorative effects of caffeine for any outcome variables.
The findings do not support the use of caffeine as a means for enhancing human function or as an antidote to the negative effects of sleep loss.
直到最近，在研究膳食咖啡因的净效应时，很少有人考虑咖啡因戒断和戒断逆转的混杂效应。
通过纳入一项涉及睡眠限制的操作，本研究旨在扩展近期研究结果，这些研究对咖啡因戒断和戒断逆转进行了控制。该研究的主要目的是研究咖啡因的净效应，以及睡眠限制后其潜在的恢复作用，对脑电图、表现和情绪的影响。
采用随机交叉设计，15名参与者在正常睡眠或睡眠限制后，连续四周每天三次交替摄入安慰剂和咖啡因（1.75毫克/千克）。在闭眼、睁眼和执行警觉任务时，在32个部位测量脑电图活动。
在δ和β频段发现了咖啡因的适度效应，但在θ或α频段未观察到咖啡因的主要效应。总体而言，咖啡因对脑电图活动的影响相对较少、较弱且不一致，没有发现咖啡因对任何结果变量有净恢复作用的证据。
这些发现不支持将咖啡因用作增强人类功能的手段或作为睡眠不足负面影响的解药。
