This article was first published in听
Some old wives鈥� tales are easy to dismiss. We all know that masturbating won鈥檛 really make your palms grow hair and that neither the position of your belly nor your internal temperature can predict the sex of your baby. However, other old wives鈥� tales are more difficult to dismiss. White spots on our nails being caused by calcium deficiency seems plausible, even though it鈥檚 untrue. Some old wives鈥� tales aren鈥檛 old wives鈥� tales at all, because an old wives鈥� tale is, by definition, untrue, and some actually are true!
While it鈥檚 important to stay skeptical when taking advice from adages with no clear origins, it turns out that some of these old sayings aren鈥檛 as silly as they may seem, once you take a look at the science behind them.
You Can鈥檛 Swim after Eating: Old Wives鈥� Tale
If you鈥檝e ever had a lakeside picnic or grabbed lunch at a water park, you鈥檝e probably heard (or more likely been told by a well-meaning parent) not to swim for 1鈥�2 hours after eating. The reasoning behind this warning is that eating causes your body to divert blood away from your muscles, like arms and legs, in favor of your digestive system. The logic follows that swimming in this state will result in听, which can increase your risk of drowning. While this idea certainly seems plausible, there is no evidence to support it.
Surely if digestion is diverting an appreciable amount of blood away from the muscles, swimming times would reflect that, right? Well,听听had subjects swim 100 yards freestyle at various times (0.5, 1, 1.5, 2, 2.5, and 3 hours) after eating and found no significant difference between times. What if we examine the heart itself?听听looked for changes in electrocardiograms following distension of the stomach, either by a large meal or a balloon and found no changes compared to before eating or ballooning.
Most damningly, according to听听conducted by the Red Cross Scientific Advisory Council, there are 鈥渘o reported cases of eating before swimming causing or contributing to fatal or non-fatal drowning.鈥�
Rest assured that you can have your lunch and swim after it too. Although perhaps skip the beer.听听of drownings can be directly听听to alcohol consumption.
If You Shave Your Hair, It Will Grow Back Faster, Darker, and/or Coarser: Old Wives鈥� Tale
Fun fact: About two years ago, I shaved my head. Since then, my hair has grown back, and funnily enough, it鈥檚 still the same color and texture as it was before. Despite holding the evidence of this myth鈥檚 mythical nature on our literal faces, heads, legs, and underarms, the idea that shaved hair will grow back darker, coarser, faster, or just generally 鈥渕ore鈥� is pervasive. Think about it. If our hair grew back longer, darker, or coarser, surely we鈥檇 have noticed a general change in its appearance after a lifetime of shaving.
The root of this old wives鈥� tale lies in, well, hair鈥檚 roots. At their tips, hairs are thin and tapered, but closer to the hair follicle they鈥檙e thicker. So, when you shave off the part of the hair that鈥檚 above the skin, the part that emerges in a couple of days (or hours) is the thicker root, leading to the appearance that the hair has grown back thicker or coarser. However, as the hair grows back out,听, leaving it looking the same as it did before you sliced it. If you wax instead of shaving your hair, you may avoid this temporarily thicker-looking phenomenon. Because wax听, the entire hair needs to regrow, meaning that it鈥檒l be the tapered end that emerges from the skin rather than the thicker root.
The darker appearances of new hairs can also be blamed on photobleaching, or rather the lack thereof. UV rays from the sun can break down the melanin pigments in our hair, just like听chemical bleaches听do. New hairs have not been exposed to the sun like their elder counterparts and thus may actually be slightly darker. Interestingly, researchers at 23andMe have听听forty-eight genetic markers that may influence hair photobleaching, which may explain why my hair turns blonde in the summer but my dad鈥檚 hair remains stubbornly dark.
Never Wake a Sleepwalker: Old Wives鈥� Truth
Stories about my sleepwalking are some of my favorites to tell at parties. They鈥檙e the ultimate way to tell hilarious tales about silly things I鈥檝e done while not being culpable for my actions. On that note, I once got out of bed and went to the living room, ruffled my boyfriend鈥檚 hair, and told him to 鈥渆at better food鈥� before returning to bed.
Living with me, one of the things he had to learn early was that there actually is some truth to the adage of 鈥渘ever wake a sleepwalker.鈥� No, not because you can send them into shock or trigger a heart attack, but for your safety.
Sleepwalking usually occurs during the third stage of non-REM sleep, when we are most deeply asleep. Researchers can monitor the electrical activity of the brain using electroencephalography, and in 2011 a听听found that both wake-like and sleep-like brain patterns coexist at the same time. They hypothesize that sleep disorders involving unusual behaviors while asleep (also called parasomnias) could be due to an imbalance between these two states.
One such parasomnia is sleep inertia, also known as sleep drunkenness, wherein following forced arousal, the cognitive impairment from sleep can remain for up to tens of minutes. During this period, the individual can be confused, impulsive, and even violent. There are听听of recently awoken people harming or even killing people around them. It鈥檚 important to note that sleep drunkenness can occur anytime someone is woken from a deep sleep, whether they鈥檙e sleepwalking or not.
In a legal sense, a person who does a crime while sleepwalking, or when sleep drunk, is not culpable for their actions. The defense is called听听because the individual is seen as acting as an automaton, not in control of their actions and with no motivation for the crime. You may be surprised to read just听听sleepwalking homicides have occurred, one of the more recent being only听听in Canada.
So, what should you do if not wake a sleepwalker? Take a page from my boyfriend鈥檚 book and听听guide them back to bed. But do make sure to tell them about it in the morning, because they probably won鈥檛 remember a thing.
Sitting Too Close to the TV Will Make You Go Blind: Old Wives鈥� Tale
The basis of TV-proximity-based fears seems to be a 1967听. The increased voltage found in new color televisions caused a radiation output that听听what the federal U.S. government deemed to be safe. As many as 112,000 TVs were affected, and the 1968 Radiation Control for Health and Safety Act was created as a result.
Funny enough, despite the large recall and general public worry, the radiation-emitting TV sets only posed a risk to those who spent excessive amounts of time sitting directly below them. If a more normal viewing position was taken (sitting roughly six feet away from the screen with it positioned at eye level), the risk was negligible. Luckily,听听televisions and computers release little, if any, radiation.
In terms of your eye health, despite what you may think when your eyes are red and sore after working all day on your new听Skeptical Inquirer听article, screens鈥攂e they television, computer, or cellular鈥攁re not dangerous in the long term. While often given scary names like 鈥�,鈥� the dry, red, blurry eyes that come accompanied by headaches and neck pain after a lot of screen time are more properly known as eyestrain and are temporary.
Eyestrain results mostly from forcing our eye (ciliary) muscles to contract for hours on end to keep our screens in focus. Like any muscle, our ciliary muscles get tired and need breaks, hence why most eyestrain can be remedied by a good night鈥檚 rest. Glare on our screen causes us to squint, further stressing our muscles.
Another important aspect is听. Humans normally blink about twenty times per minute, but computer-users can blink as few as seven times per minute. This causes our corneas to dry out and our vision to appear foggy.
Rest assured, however, that no matter how little you blink, how hard you squint, or how close to your face you put your phone, your vision听听in the long term.
As for the blue light emanating from your iPhone, its effects are limited to听, a hormone that regulates our sleep timing. There鈥檚听听that blue light blocking glasses (or the new night modes available on phones and computers) can help if you鈥檝e been having trouble falling asleep. However, if you鈥檙e worried about blue light causing damage to your eyes long term,听.
Feed a Cold, Starve a Fever: Old Wives鈥� Tale with a Kernel of Truth
When afflicted with an illness, like the common cold, it鈥檚 a natural response to lose your appetite. That makes the second half of this saying easy enough to comply with. As for the first part, beyond chicken soup and maybe some Jell-O, eating while ill can be a difficult task. Even drinking is hard enough that patients often need supplemental fluids when sick. But hey, if it works, hand me the soup. I鈥檒l suffer through some unwanted meals if it makes me feel better faster. But will it?
This piece of outdated medical advice听听to听听the idea that eating can raise the bodily temperature, something that could be beneficial if fighting off an infection, but detrimental if one is already nursing a fever. It鈥檚 also worth remembering that it was once thought that the common cold could be caught by exposing oneself to cold weather and that heat was a remedy.
While it is true that eating can help raise your body鈥檚 temperature, that鈥檚 not the part of this aphorism that may be true. There are some theories as to how and why starving yourself when ill may help you fight an infection, but it鈥檚 not specific to a fever.
As you likely know, fevers can help your body fight pathogens, both by creating an inhospitably hot environment that will eliminate some infectious agents and by increasing the rate of reactions inside your body that contribute to your immune response. In a similar vein, some researchers believe that anorexia, the medical term for a loss of appetite, is a bodily response to an infection designed to help you heal faster
There are a few听听to support anorexia as a听. First, anorexia is extremely widespread, occurring in almost all mammals. Second, behaviorally, a lack of appetite would keep mammals from leaving the safety of their nest/burrow/home to search for food while cognitively and physically impaired, which would also help reduce heat loss due to movement and therefore preserve the fever the body has so carefully created. Third, not eating will reduce the micronutrients like iron available in the blood plasma that pathogens would use for their own purposes, and last, various immune functions, like the activation of macrophages, seems to be increased under starvation conditions
While mice studies cannot be extrapolated to humans, an interesting听听infected mice with听Listeria monocytogenes听and found that those kept from eating had a mortality rate of 40 percent compared to a mortality rate of 90 percent in those who were force-fed.
We鈥檒l need to see some high-quality research on humans before we make any definitive changes to how we treat illnesses regarding diet, but in the meantime, if you鈥檙e not feeling hungry while home sick, don鈥檛 force yourself to eat.听听that much more important than what you eat when sick is what you drink, so make avoiding dehydration your priority.
