What you need to know about melatonin

ATLANTA - "And I was trying to sleep naturally, and not wanting to take something prescription," she says.

So, Smith's doctor, Sherika Newman of Montgomery Medical Associates recommended she try the supplement melatonin. It's a hormone produced by our body that regulates our internal clock -- signaling when it's time to sleep. When our melatonin levels rise, typically in the evening, we feel sleepy. When they drop, usually during the day, we're more alert. Dr. Newman says if you travel, work odd hours, or have trouble falling asleep, melatonin might help.

"What people have seen is, when they start taking it, is their wakes cycle does change," Dr. Newman says.  "They're less irritable, less fatigued in the morning. Because melatonin helps you initiate, maintain and normalize your sleep schedule."

If you're a frequent flyer, you've probably been hit with jet lag, like Margie Smith did on a trip to Italy.

"Well, I'm not a good sleeper to begin with, I'm very restless at night," Smith says. "So, once I get kind of out of whack with my sleeping, it's hard to get back into a good sleep pattern."

When Smith changed several time zones at once, it threw off her body clock.

That made falling asleep at her regular bedtime tough.

Melatonin can cause side effects like grogginess, headache and vivid dreams.

So, Dr. Newman says talk to your doctor about whether it's right for you.

"We always recommend everything in medicine, even though it's natural, to start low and go slow," she says.  "So, (start with a) low dose, 0.5 milligrams.  And I wouldn't recommend doses over .10 milligrams."

When you take the supplement is important, too.  If you're trying to fall asleep, take melatonin about 30 minutes before your bedtime. If you're trying to shift your sleep window, take the supplement about two hours before you want to go to sleep. Margie Smith is still taking melatonin, long after her Italy trip, because, she says, it helps her sleep.

"It's definitely better," Smith says.  "I still don't sleep all through the night, but my sleep is more sound."