Effects of Placebo Expectation and/or Caffeine on Alertness during 30h Sleep Deprivation

Objective: To study caffeine and/or placebo implication as countermeasures during sleep deprivation (SD). Methods: A double-blind, within-subjects and counterbalanced design was employed and five trials were conducted. Subjects were exposed to 30h SD in each trial. No medicine was administrated in control trial while placebo 200mg, caffeine 200mg, caffeine 400mg and the combination of caffeine (200mg) and placebo (200mg) were administered, respectively in the other trials. Letter Cancellation Test was used to assess the alertness. Result: The correct concealing numbers per minute (CCNM) of the combination of caffeine and placebo (62.36±7.31/min), caffeine 400mg(55.88±6.54/min) and caffeine 200mg (59.48±6.52/min) were more than that of control(46.80±5.35 /min), P0.05. Compared with CCNM of placebo 200mg(52.06±9.30 /min), that of the combination was higher (P0.05). Conclusion: Caffeine and the combination of caffeine and placebo expectation can increase alertness.