We’ve all heard our share of advice, and it’s probably safe to assume that they are told with the best of intentions. However, there is a wealth of health related information out there that is simply not accurate and yet has somehow withstood the test of time, elevating itself into the realm of “medical mythology.” These myths are, for the most part, pretty harmless, though they can have a profound effect on our way of life, despite their inaccuracies.

Thus, in an effort to bring a little more clarity into the world, we at Healthy Theory would like to debunk some of these misconceptions and set the record straight. So here are 35 medical myths and the real story behind them.

1. Feed a cold, starve a fever. In the end, it’s better to feed both, because food is fuel, and fuel is essential for all bodily functions, including battling a fever, which just so happens to increase your metabolism and by extension, your body’s need for food. (DukeHealth)

2. Reading in dim light will ruin your eyesight. While adequate lighting will lessen eye strain, reading in dim light will not cause permanent damage to the structure of your eyes, making you more nearsighted. (British Medical Journal)

3. Cold weather causes colds. Despite its name, colds aren't really caused by being cold. While it's true that we get more colds during cold weather, it is due to the fact that more people are indoors and thus brings us in greater contact with sick individuals and their germs. It's the contact with other people who are sick that makes us sick. Not cold weather, wet hair, nor drafts. (New York Times)

4. Your head is the greatest source of body heat loss. Your body will lose heat wherever it is uncovered and exposed to the elements. (British Medical Journal)

5. Cracking your knuckles will lead to arthritis. Sure, it may be distracting and even a bit annoying to the people around you, but it won’t increase the likelihood of arthritis later in life. (New York Times)

6. Sugar makes kids hyperactive. It turns out that numerous studies have refuted this claim. In fact, studies have shown that sugar’s effect on children is more of a perception than a fact. It's all in parents' minds. (British Medical Journal)

7. Never wake a sleepwalker. Contrary to popular belief, no sleepwalker has ever died as a result of being woken up. (USA Today)

8. We only use 10% of our brains. Although it'd be nice to think that our mental capacity is actually a lot larger than we currently have, brain studies haven't showed 90% of our brain as inactive. (British Medical Journal)

9. You should wait an hour after eating before going swimming. Exercising after eating a big meal may make people feel uncomfortable, but it won't cause life-threatening cramps. (USA Today)

10. Heart disease is not a concern because you’re slim. Contrary to stereotypes and public opinion, many overweight and obese people are metabolically healthy, while large numbers of slim people have health problems typically associated with obesity. (New York Times)

11. Antibiotics will hamper the effectiveness of birth control pills. Research has shown the there is no relationship between the two. (New York Times)

12. Having sex can cause a heart attack in men. The risk is hugely exaggerated by film and books. A 50-year-old non-smoking male has a one in a million chance of suffering a heart attack in any hour. Having sex increases that to two in a million. It does "double the risk" but the total risk is still neglible. (Times Online)

13. Shaving makes hair grow back faster and coarser. Shaving your hair won’t change its texture or rate of growth. It may initially appear coarse due to the blunt ends from cutting, but it will eventually taper off and look exactly like the hair you cut off. (British Medical Journal)

14. Drinking milk increases your phlegm. Studies have shown that having a cold and drinking milk did not increase either the weight of nasal secretions or the incidence of coughing and congestion. (New York Times)

15. Single people have better sex lives than married couples. Sure, the grass may seem greener to some married people, but singles go through their share of time being alone, such that married people end up having more sex in the long run. Also, it seems that married couples are more likely to achieve orgasms and engage in oral sex, which is reason enough to tie the knot. (New York Times)

16. You should have a bowel movement at least once a day. Not completely true or false. Normal healthy individuals don’t necessarily have to do a “#2” every day, though doing so might have an influence on your state of contentment. (New York Times)

17. Double dipping your chip is no big deal. Then again, it is a big deal. Double dipping transfers thousands of bacteria from your mouth into that guacamole with every scoop. So do your friends and yourself a favor and grab a fresh chip before you dip. (New York Times)

18. Food that is quickly retrieved from the floor is fine to eat. Actually, food that hits the floor picks up bacteria on contact, though less so on a carpeted floor. (New York Times)

19. Using cell phones in hospitals is dangerous. Not true, according to a study by the Mayo Clinic, which found that the incidence of interference from cell phones was negligible, at best. (British Medical Journal)

20. You should drink eight glasses of water each day. Most of us get plenty of liquids from food. And too much water can lead to a dangerous condition known as water intoxication, which in some cases can be fatal. (British Medical Journal)

21. The flu vaccine causes the Flu. The injectable flu vaccines do not contain complete viruses capable of causing the Flu. It's more likely you caught it waiting to get the vaccine, or you already had it and began showing symptoms shortly after. The only vaccine that contains the actual live (but weakened) virus is FluMist, which is sprayed up your nose rather than injected. Theoretically it may cause a mild case of influenza. (WebMD)

22. Fevers cause brain damage. Normal fevers do not cause brain damage, and is a sign that your body is fighting off an infection. Although it is important to find the source of the fever in case it is caused by something more serious like meningitis or pneumonia, it is largely therapeutic rather than dangerous. (WebMD)

23. Hair and fingernails continue to grow after death. It may only seem that way because dehydration makes the skin shrink back, making hair and nails look longer than before. (British Medical Journal)

24. Eating turkey makes you sleepy. True, turkey has tryptophan, but not any more than many other food items, such as chicken and beef. It's not the turkey, but the rich, decadent meal that usually accompanies it (Thanksgiving dinner) that causes the sleepiness. (British Medical Journal)

25. Chewing gum stays in your body for 7 years. It's true that gum is not digestible in the human body, but it just passes through whole in your system and is eliminated at the same rate as other foods. (The New York Times)

26. You can prevent colds with vitamin C, echinacea or zinc. Studies have shown no effect in relieving or preventing colds. (USA Today)

27. Adding cereal to a baby's diet will help him sleep longer. Bad news for sleep-deprived parents everywhere, but studies dating back to 1974 has shown babies who are fed cereal get no more sleep than other babies. (USA Today)

28. Teething causes a fever. Studies show that teething babies are no more likely to run a fever than others. (USA Today)

29. Don't let someone with a concussion fall asleep. As long as they've seen a doctor and don't need further treatment, it's okay to let them sleep. (USA Today)

30. The hand drier in public restrooms spread germs. Air sampled around the driers in various public restrooms were found to have no increase in bacteria. The real concern is having to touch that button to start it. (ABC News)

31. Suicides are highest over the holidays. Around the world, suicides peak in warmer months and are actually lowest in the winter. (British Medical Journal)

32. Poinsettias are poisonous. Analysis of the plant has shown no toxicity, even at large amounts. (British Medical Journal)

33. Eating at night makes you fat. The time you eat your meals is not what's important -- it's how much you eat. Time again diet fads have proved that if you simply can't take in more calories than you use, without gaining weight. (British Medical Journal)

34. You can cure a hangover. A systematic review of possible cures were found to be ineffective against curing hangovers. A hangover is simply caused by excess alcohol consumption. (British Medical Journal)

35. Cholesterol is mostly affected by your diet. Only a third of cholesterol in the body comes from your diet. This means food items that are known to be high in cholesterol (for example, eggs and shellfish) can be enjoyed freely. Of course, being overweight can lead to high cholesterol, so not too freely. (The Sun)

Also check out Dr. Aaron Carroll and Dr. Rachel Vreeman's (authors of the British Medical Journal articles cited above) book called Don't Swallow Your Gum! with plenty more medical myths debunked.

Fortunately, most of these myths will not cause life-threatening conditions and may simply boil down to a little common sense. If you have any concerns or doubts, speak with your physician, and keep checking in at Healthy Theory, where our goal is to improve your quality of life by keeping you informed.