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Wakefulness caused by caffeine


Certain psychotropic effects of caffeine were investigated in doubleblind placebo-controlled experiments with 230 medical students.

  1. 1.

    Caffeine prolonged the time required to fall asleep and disturbed the soundness of sleep when administered in a dose of 150 or 200 mg in decaffeinated coffee shortly before bedtime.

  2. 2.

    Caffeine caused distinctly less wakefulness in subjects who habitually drank a great deal of coffee.

  3. 3.

    Some subjects among those who drank most coffee manifested morning headache after about 18 hours abstinence and this headache was prevented by a single dose of 150 mg the previous evening.

  4. 4.

    An interesting “reverse placebo effect” was revealed, whereby subjects receiving known caffeine tended to minimize its sleep-disturbing effects.

  5. 5.

    Important advantages in the use of medical students as subjects in experiments of this kind are pointed out, quite apart from any didactic value of such exercises.

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Additional information

Dedicated to my teacher, colleague, and friend, Professor Otto Krayer, on the occasion of his sixty-fifth birthday. A preliminary report of this work has been published (Goldstein and Warren 1961).

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Goldstein, A. Wakefulness caused by caffeine. Naunyn-Schmiedebergs Arch. exp. Path. u. Pharmak. 248, 269–278 (1964).

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  • Placebo
  • Caffeine
  • Single Dose
  • Medical Student
  • Placebo Effect