Naps vs. caffeine vs. more night sleep

What's the best way to beat afternoon sleepiness? (drumroll) Go to sleep! Loughborough University researchers compared three methods to beat normal daytime sleepiness: more sleep at night, an afternoon nap earlier that day, or caffeine. During the study, volunteers who either napped, slept late, or took a caffeine pill, were put in a quiet room and invited to close their eyes. The researchers then compared how long it took them to fall asleep. From Science News:

The researchers compared sleeping in for 90 minutes each morning to taking a 20-minute nap at 2:30 p.m. or taking 150 milligrams of caffeine (equivalent to about two cups of coffee) at 2:00 p.m…

When the volunteers did nothing, they fell asleep within nine minutes on average when tested at 3:30 in the afternoon. Sleeping late kept people awake only a minute longer on average than did doing nothing. Caffeine worked better, keeping people awake for about 12 minutes longer on average.

But nothing beat a nap. After a 20-minute nap, people nearly doubled the amount of time it took to fall asleep when tested later in the afternoon, indicating that they were no longer sleepy. None of the measures impaired people's ability to fall asleep at night.