Sleep Deprivation: A Mini Review

Qi-Chang Lin; Dong-Dong Chen

doi:10.36876/smjsd.1005

Caffeine and Placebo Expectation

Journal of Psychophysiology ◽

10.1027/0269-8803.21.2.91 ◽

2007 ◽

Vol 21 (2) ◽

pp. 91-99 ◽

Cited By ~ 8

Author(s):

Yunfeng Sun ◽

Yinling Zhang ◽

Ning He ◽

Xufeng Liu ◽

Danmin Miao

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Sleep Deprivation ◽

Cognitive Performance ◽

Cognitive Functions ◽

Cardiovascular Regulation ◽

Double Blind ◽

Positive Effects ◽

Pressure Tests ◽

Healthy Males

Abstract. Caffeine placebo expectation seems to improve vigilance and cognitive performance. This study investigated the effect of caffeine and placebo expectation on vigilance and cognitive performance during 28 h sleep deprivation. Ten healthy males volunteered to take part in the double-blind, cross-over study, which required participants to complete five treatment periods of 28 h separated by 1-week wash-out intervals. The treatments were no substance (Control); caffeine 200 mg at 00:00 (C200); placebo 200 mg at 00:00 (P200); twice caffeine 200 mg at 00:00 and 04:00 (C200-C200); caffeine 200 mg at 00:00 and placebo 200 mg at 04:00 (C200-P200). Participants were told that all capsules were caffeine and given information about the effects of caffeine to increase expectation. Vigilance was assessed by a three-letter cancellation test, cognitive functions by the continuous addition test and Stroop test, and cardiovascular regulation by heart rate and blood pressure. Tests were performed bihourly from 00:00 to 10:00 of the second day. Results indicated that C200-P200 and C200-C200 were more alert (p < .05) than Control and P200. Their cognitive functions were higher (p < .05) than Control and P200. Also, C200-P200 scored higher than C200 in the letter cancellation task (p < .05). No test showed any significant differences between C200-P200 and C200-C200. The results demonstrated that the combination of caffeine 200 mg and placebo 200 mg expectation exerted prolonged positive effects on vigilance and cognitive performance.

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