Who, What, Why: How long is the ideal nap?

We've discussed this before, but this article by The BBC brings up an interesting perspective. Author Tom Geoghegan starts the article with this point,

Air traffic controllers in the US have been advised to take 26-minute naps, after a string of incidents involving workers falling asleep. So is 26 minutes the ideal length of time for a nap?

I've discussed before that a 20-30 minute nap is ideal, so it would make sense that 25/26 minutes is key. However, some believe that 20 minutes is too long. Other than equipping yourself with caffeine so that by the time it kicks in you're up, "once you get beyond 20 minutes, you risk a deep sleep and you can be much more groggy when you wake up." (Jim Horne, Sleep Research Council, UK).

So while 20 minute naps can increase alertness for hours, you also run the risk of just feeling more tired. I believe that comes with any nap though. Just remember to nap no longer than an hour and not too close to your bed time, and you should be fine. If you want to double you're alertness you can drink coffee too before you shut your eyes.

As for Air Traffic Controllers, it's best you get a full nights rest so you don't need a nap.