By Mary Kay Kleist

(CBS) — Many Americans struggle with feeling tired and in desperate need of a nap. One researcher says something that may happen during a nap could be a clue as to whether you’re actually sleep-deprived.

CBS 2’s Mary Kay Kleist explains.

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In a bed or on a bench, even on the subway, you see people catching a snooze.

“I think napping is number one. You have to nap, no matter what,” Edwin Torres says.

Research shows there are clear benefits to some quick shuteye.

Sleep researcher David Dinges of Pennsylvania’s Perelman School of Medicine says: “It can help you compensate for a lifestyle of reduced sleep at night, make your alertness better. It can improve your memory.”

But naps can also be counter-productive.

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“You have to understand that you’re taking a dose of sleep you have to think about it the way you might consume a dose of food, and then you don’t want to over-eat and you don’t want to under-eat,” Dinges says.

Experts say the ideal time for nap is generally between 1 p.m. and 4 p.m. Napping later than that can interfere with nighttime sleep.

For a quick boost of alertness, try a 10- to 20-minute power nap. And to help with memory, 60 minutes of snoozing may do more good. The downside to a longer nap is it can leave you groggy.

“It can take as much as 20, 30 minutes to overcome. It’s best to get light on you and move around, and take a shower, or drink coffee to overcome it,” Dinges says.

Naps can help you re-charge, but they can also be an indication that you’re sleep-deprived. Dr. Rafael Pelayo is a sleep expert at Standford University. He said, “When you take a short nap, normally you should not be dreaming. If you’re dreaming during a nap, that means that you’re not getting enough sleep overall.”

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Experts say it doesn’t matter where you nap. But to avoid a deep sleep, it’s best to sit slightly upright. And for people with sleep conditions like insomnia or sleep apnea, napping isn’t recommended.

Mary Kay Kleist