Sleep Extension versus Nap or Coffee – Review

HORNE, J., ANDERSON, C. and PLATTEN, C. (2008), Sleep extension versus nap or coffee, within the context of ‘sleep debt’. Journal of Sleep Research, 17: 432–436. doi: 10.1111/j.1365-2869.2008.00680.x

An interesting article comparing three methods of reducing daytime sleepiness against a control group.

The setup was to test one countermeasure each week, in one test day a week, to see the effects of:

  1. usual sleep (control group)
  2. sleep extension (sleeping up to 90 minutes longer at night)
  3. afternoon nap (20 minutes sleep within 30 minute period)
  4. afternoon coffee (2 cups of coffee)

The effect of each intervention was measured with the three following tools:

  • MSLT – Multi Sleep Latency Test (at several times a day, it is measured how long it takes for participants to fall asleep, or go to sleep stage 1, after being asked to do so. The longer this takes, the less sleepy the participant is)
  • KSS – self-reflection of sleepiness
  • PVT – measurement of reaction times

The outcome of the experiments was that a nap and caffeine had equally reviving effects, with a surprising outcome that caffeine did not have a rebound effect later in the evening, as you might expect. Sleeping longer was slightly less effective.

Something else I have read about is a caffeinated nap, where you drink the caffeine, and during the time it takes for the caffeine to take effect, which is about half an hour, you take a nap. This way, when you wake up, you are refreshed by the nap and the caffeine. This protocol was not tested in this study, but it would be interesting to see how it compares, as other literature has reported positive effects.

One last thin that was interesting in this paper, was that the authors’ earlier research revealed that

most of those who would like to have more daily sleep, would not actually take it if given a free hour in the day when there were attractive waking alternatives.

This would negatively impact the advice to take a nap, even if people knew the benefits. Perhaps when faced with the choice, they would rather take the coffee than a nap? On the other hand, perhaps naps could relieve chronic sleep deprivation, where coffee might not.

If you want to read more about sleep, see this post.

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