With the year's end arriving, the British Medical Journal asked two physicians take a look at some of those old adages that everyone repeats each holiday season. Looking at six of these, the doctors found that some might have reasons behind them, but found no solid backing after a large number of studies.
"We're trying to just show that it's important for us to examine commonly held beliefs," said Dr. Aaron E. Carroll, director of the Center for Health Policy and Professionalism Research at the Indiana University School of Medicine. "There's good science to show that these beliefs are incorrect, that they're myths, and yet many people still believe them."
This was the second straight year that Carroll and his colleague, Dr. Rachel C. Vreeman, took a look at some holiday myths for the journal.
While stressing that most of the myths are not harmful, Carroll said they may cause people to change their behavior unnecessarily.
"Some of it's not a good idea, and some of it is perfectly good to question," he said.
Here are the six myths they looked at, which they and other doctors hope to dispell:
Sugar Makes Kids Hyperactive
Carroll and Vreeman noted in their article that 12 separate trials failed to show any difference in children's behavior after consuming sugar, even those with ADHD and other conditions considered "sensitive" to sugar.
"I probably get more questions about that than almost anything else," said Keith Ayoob, a registered dietitian and an associate professor of pediatrics at Albert Einstein College of Medicine in New York City, who was not involved with the writing of the article.
"While sugar can give a quick burst of energy, " he said, "it doesn't cause hyperactivity and there are tons of studies to show this."
Ayoob said the myth exists for not only sugar, but food dyes as well.
Carroll and Vreeman also note that parents appear to be sensitive to this myth, as studies they looked at showed that parents would rate their children as being more hyperactive if the children had just eaten sugar, even if the child's behavior was not different.
Ayoob notes that sugar gets too much credit for its effects.
"If it were that easy to get a buzz, adults would be popping hard candy all day long," he said.
But that doesn't mean parents shouldn't limit their children's sugar intake, because a lot of the sugar kids want isn't healthy.
"I don't think kids should be given huge amounts of sugar by any means," said Ayoob, "but let's not attribute more to sugar than is really there."
Suicides Increase During the Holiday Season
Carroll and Vreeman point to a study of 35 years in the United States to prove that the belief that suicides increase at holiday time is a myth.
They note that suicide peaks actually tend to come in the warmer months of the year, and that among youths, suicide rates tend to peak at the close of a school year, because, they speculate, those adolescents do not have their support system anymore.
But while suicides are not an annual epidemic around the holidays, this holiday season may be a bit different, said Mark Kaplan, a professor of community health at Portland State University and a member of the Suicide Prevention Action Network USA's National Scientific Advisory Council. He notes that the economic downturn may contribute to a sense of desperation not seen in the past.
"How do you separate the current holiday seasons from everything else going on?" Kaplan said. "This holiday season is quite different from past holiday seasons... It's challenging people's emotions far more than in the past."
Poinsettias Are Poisonous
While the red and green flower arrangements are popular at Christmas time, many people worry that the plants themselves are poisonous.
Carroll and Vreeman noted that despite hundreds of thousands of calls to poison control centers over poinsettia poisonings, none of those cases resulted in death. They also noted a study showing that rats could consume the equivalent of 500 to 600 leaves without problems.
But Ayoob notes that we should still avoid making any house plant an entrée.
"It's probably a good idea to make sure that your kids don't eat the house plants on any level," he said, noting that paint, glitter and chemicals applied to the plant could cause stomach problems for youngsters and pets.
Even if the plant itself is not poisonous, "I still wouldn't turn it into a mojito," said Ayoob.
You Lose Half Your Body Heat Through Your Head
Wearing a hat in the winter may help keep you warm, but it isn't necessarily more critical than the rest of your body.
Carroll and Vreeman note that this myth even made it into a U.S. Army field manual for survival. They suspect the myth originated when, for a military study, scientists put subjects in arctic survival suits without hats. Had they put them in swimsuits, the pair said, the heat loss from the head probably would have been closer to 10 percent.
"You don't lose 50 percent of your body heat through your head," said Dr. David Cook, an emergency physician with Christiana Care in Newark, Del., and a member of the public relations committee for the American College of Emergency Physicians.
Ten percent, he said is probably a better estimate, because that is roughly the amount of the body's surface area that the head composes.
Cook said he remains unsure of why this myth has persisted.
"I'm not sure if it's just an old wives tale that just kind of lingered, like going outside with wet hair will give you a cold," he said. "There's a lot of things that have hung around in the form of wives' tales that haven't been disproved to people in the general public."
But Paul Pepe, chair of emergency medicine at UT Southwestern Medical Center notes that it is still important to cover your head and neck, as they will cool faster than other body parts because of wind, and it can range up to 20 or 30 percent.
"You do lose a lot of your body heat around your head and neck."
Eating a Lot at Night Will Make You Fat
Carroll and Vreeman noted that this myth may have taken hold because most heavy night-eaters are heavy eaters at all times of the day.
They note that skipping breakfast may lead to weight gain, however, because it leads people to overeat at other meals.
Ayoob said spacing out meals is the key to avoiding weight gain, since it keeps calorie consumption level throughout the day. And total calories will matter more than when they are eaten.
"Ultimately, it's all about the calories," he said. "That said, sometimes when people eat a lot at night, they're going to wake up not wanting to eat breakfast."
And that is where the weight gain problems can begin. Also, notes Ayoob, heavy eating at night isn't a good idea because it can prevent you from getting quality rest.
"It's really hard when you've got a meal the size of a basketball under your ribs to go to sleep."
You Can Cure a Hangover
The good news, said Carroll and Vreeman, is that hangovers are completely preventable.
"The most effective way to avoid a hangover is to consume alcohol only in moderation or not at all," they wrote.
Unfortunately, notes Ayoob, most don't want to take that route.
"People want to negotiate with their bodies," he said.
But Carroll and Vreeman looked at a number of supposed cures that have been tested and found that those negotiations seem to always come to a standstill.
They looked at studies for aspirin, bananas and Vegemite and water, and found none of them would prevent the day-after headaches.
Ayoob notes that while moderation is preached, many do not want to follow the guidelines, which limit women to one drink and men to two.
Also, he said, it has almost become a joke when taking medical histories for drinking, as people are reluctant to admit how much they actually consume.
While many refer to themselves as "social drinkers," he said, ""Way too many people are getting way more social."
Ayoob noted that the only way to end a hangover is to wait it out.
"There is no really hard evidence that you can prevent a hangover, except with time and fluids," he said.
The message of these myths, say the authors of the article, is that people should be more inquisitive when they hear these kinds of statements, whether from a parent, teacher or doctor.
"If a doctor doesn't have a good answer, they should go find out why," said Carroll.
"We're trying to illustrate that you should ask why. It's always a good idea to ask why. I guess we're trying to promote a healthy skepticism, especially when it comes to health and medical issues."