A pilot study investigating the impact of a caffeine-nap on alertness during a simulated night shift

Chronobiol Int. 2020 Sep-Oct;37(9-10):1469-1473. doi: 10.1080/07420528.2020.1804922. Epub 2020 Aug 20.


Consuming coffee immediately prior to a nap, known as a caffeine-nap, has been shown to improve alertness during the day, but it is unknown whether a caffeine-nap is effective at reducing sleep inertia during the night. A simulated shiftwork cross-over laboratory study was conducted whereby participants (N = 6, 4 F, 21-36y) consumed 200 mg of caffeine, or decaffeinated coffee (placebo), immediately prior to a 30 min nap opportunity at 03:30 h. Compared to placebo, the caffeine-nap resulted in improved vigilant attention and subjective fatigue in the 45 min post-nap opportunity. The caffeine-nap may be useful in reducing sleep inertia in shift workers who nap on nightshift.

Keywords: Coffee; fatigue countermeasure; napping; shiftwork; sleep inertia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Attention
  • Caffeine*
  • Circadian Rhythm
  • Humans
  • Pilot Projects
  • Psychomotor Performance
  • Sleep
  • Sleep Deprivation*


  • Caffeine