June 10, 2008 (Baltimore) -- A short siesta is the best way to combat the mid-afternoon nods, a small study suggests.
A jolt of java may also help to overcome daytime sleepiness, British researchers say.
What doesn't seem to work, the study showed, is trying to grab some extra winks in the morning in an effort to ward off problems later in the day.
"Of the three, the nap is best," says Clare Anderson, PhD, of the Sleep Research Centre at Loughborough University in Leicestershire, England. "But coffee beats nothing."
The so-called afternoon dip -- a high propensity to nod off between 1 p.m. and 3 p.m. despite a good night's rest -- is a well-known phenomenon.
Nap Best, but Coffee Helps Too
The study involved 20 healthy 20-somethings who were what the researchers call "good sleepers," averaging nearly seven-and-one-half hours of uninterrupted sleep a night.
All underwent three interventions designed to combat daytime sleepiness: A 20-minute nap at 2:30 p.m.; a strong cup of coffee containing 150 milligrams of caffeine at 2 p.m.; or 90 extra minutes of sleep in the morning. The three nod-fighters were given a week apart.
Testing in the sleep lab showed that:
- The nap improved daytime sleepiness, compared to both no intervention and getting extra winks in the morning.
- A cup of coffee reduced sleepiness in the afternoon, compared to doing nothing.
- An extra 90 minutes of sleep was associated with no improvement in daytime sleepiness.
If you're a normal sleeper, getting seven or eight hours of sleep a night, then getting extra sleep in the morning doesn't really help, Anderson says.
None of the interventions -- not even the mid-day caffeine boost -- kept the participants up at night.
That could be because people who didn't normally consume caffeinated drinks were excluded from the study, she says. "In the U.K., we're used to drinking a fair amount of [caffeinated] tea every day, so the cup of coffee didn't affect their sleep."
20 Minutes Optimal Length for Midday Nap
American Academy of Sleep Medicine spokesman Sanjeev Kothare, MD, advises against drinking caffeinated beverages too late in the day. "If you drink one at 4 p.m., for example, it will linger in your system until almost midnight," he says.
Kothare, a sleep specialist at Harvard Medical School, notes that although siestas are encouraged in some cultures, they are typically "impractical" for Americans.
But if you can fit in a midday nap, 20 minutes is just right, he tells WebMD.
Research has shown that after a 10-minute nap, participants awoke feeling a little refreshed, but soon felt sleepy again. After a 40-minute siesta, on the other hand, they work up feeling groggy, according to Kothare.
"Twenty minutes proved optimal in terms of subsequently feeling alert," he says.