Still unknown: are you to blame for your mother's back pain for stepping on a crack?
Even
in our hyper-connected world where reliable medical knowledge is ridiculously
accessible, many health-related myths still carry on through the years. 
Hope you don't live in Texas
When discovered, these long-held false beliefs often leave the former believer at a loss to explain where the questionable information came from in the first place.
The list below contains six medical myths that have been around for a long time. See if you find anything that surprises you.
1. You can’t get
pregnant if you’re on your period.
According
to the American Pregnancy Association, this is not true.
The
Association website explains that while this is a rare occurrence, if the woman
has a shorter than typical cycle and ovulates early, a pregnancy can definitely
happen.
The science behind this is all about the timing. Surprisingly, sperm can remain viable in a woman’s reproduction system for up to five days. Therefore, if the woman has sex near the end of her period, and if ovulation happens within five days after the encounter, it’s possible that those little swimmers are still there waiting to fertilize that egg.
2. 8 Glasses of water a day are necessary for good health.
According
to the Mayo Clinic, this statement is unknowable, and you should drink whenever
you’re thirsty.
The
website goes on to explain that while water has an important role to play in
the smooth functioning of our bodies, the exact amount needed on any given day
can vary widely. Sometimes you’ll need way more, like on a hot day when you’re
sweating up a storm or days when you’re more physically active. On other days
when you’re inside relaxing on the couch, you don’t need nearly so much.
How
much water you need also depends a lot on what you choose to eat. Fruits and
vegetables, for example, have high water content and will decrease the amount
of water you need to drink.
The
bottom line is that you should pay attention when you’re feeling thirsty, and
what you choose to drink when you’re thirsty should be water.
In-Depth: How Much Water Should I Drink? We Asked 5 Experts
3. Spicy food
and stress cause ulcers.
According
to the American Academy of Family Physicians, the vast majority of ulcers are
caused by a bacteria called Helicobacter pylori (H. pylori), not spicy food or stress.
However,
some ulcers can be caused by the long-term use of aspirin and other
non-steroidal anti-inflammatory drugs (NSAIDs).
That
said, spicy food and stress worsen the discomfort, as do caffeine and alcohol,
no matter what the original cause.
4. A person with
a concussion shouldn’t be allowed to go to sleep.
A
concussion is a mild traumatic brain injury caused by a sharp blow to the head
or body that causes a sharp back and forth sloshing motion in the brain,
disrupting its activity. However, because a concussion can’t be seen on any
medical imaging, the severity of the concussion must be diagnosed by the
symptoms the patient is presenting. As with any injury, treatment of the condition
is based on the doctor’s understanding of the severity of the wound.
In
the past, it was widely believed that it’s dangerous to allow someone with a
concussion to sleep for fear they’ll slip into a coma or lose consciousness
with no one knowing. Popular thought was that concussed individuals should be
woken as often as every two hours or not be allowed to sleep at all.
However,
because rest is the way that the body heals, waking someone or denying them
sleep is counterproductive to healing. It stands to reason that allowing a
concussed person to have a good night’s sleep will do more good than being
roused every couple of hours to answer questions about how they are feeling.
5. Eggs cause
heart disease.
According
to Harvard Health, a publication of Harvard University, whole eggs don’t cause
heart disease, but excessive saturated and trans fats do.
Yes,
eggs have lots of cholesterol, and high LDL blood cholesterol (the bad type)
increases the risk of cardiovascular disease. But recent research has found
that the cholesterol in our blood doesn’t come directly from what we eat; it’s
manufactured by the liver, stimulated by the saturated and trans fats in our
diet.
In
fact, for an otherwise healthy individual, heart disease is more likely to be
caused by a combination of factors such as eating lots of fatty foods, being
overweight, not getting enough exercise, smoking, and drinking alcohol.
6. People only
use 10% of their brains.
Neurologist
Dr. Barry Gordon of Johns Hopkins School of Medicine says that the idea that we
only use 10% of our brains is so wrong it’s almost laughable.
The
Johns Hopkins website goes on to explain that the brain is a complex organ
controlling thought, memory, emotion, touch, motor skills, breathing,
temperature, hunger, and every process that regulates the body.
So,
while it’s true that all parts of our brains are not all being used at once,
that doesn’t mean that those areas are never used. Different parts of the brain
oversee the diverse activities of the body. Brushing our teeth, for instance,
might use some distinct areas of the brain that reading a book does not,
leaving some parts temporarily inactive and waiting for their turn to shine.