hates it too. Axial tilt maybe be the reason for the season, but it’s technically changing

our genes.

Hey guys julia here for DNews

Winter is rough for those of us who live in cold climates. As the wind chill dips below

zero degrees, you ask yourself, why do I live somewhere where the air HURTS MY FACE!? But

it’s not just the cold that’s rough on our bodies, it’s the lack of sunlight too.

Almost all living things have a circadian rhythm that changes with the light. From sleep

cycles to hibernation, light regulates most of life on Earth. The Earth is tilted at a

comfortable 23.5 degrees. This means that at some parts of the year the northern hemisphere

leans slightly closer to the sun and other parts of the year the southern hemisphere

gets a little cozier with the sun. And with that, it means the amount of light that reaches

your little section of the planet changes throughout the year. Those grey skies and

fading evening light can have profound changes on your body.

The change in light can cause problems like seasonal affective disorder, a condition which

brings about a low mood as levels of sunlight induced Vitamin D drop. But there’s a few

other lesser known effects of less sunlight.

In a study published in the journal Drug Metabolism & Disposition researchers found how less sunlight

changes how your body metabolizes medication. They focused on two types of immune suppressing

drugs, tacrolimus and sirolimus. Basically the more Vitamin D, the more an enzyme CYP3A4

is produced. The more of this enzyme, the faster the drugs were metabolized. While the

study focused on just these two medications, the researchers think these results might

be true for other types of medications. So the study suggests that sunlight could affect

your sensitivity to certain drugs.

One study from the American College of Cardiology, found that cholesterol levels vary from season

to season. In a large study of over 2.8 million adults, researchers from Johns Hopkins Ciccarone

Center for the Prevention of Heart Disease found that for many people, cholesterol levels

seem to be higher in the winter. The researchers think that less sunlight plays a role in these

rising levels. As we are exposed to less light during the winter, because of staying inside

and shorter days, we get less vitamin D. Another study published in the journal Menopause found

a link between more vitamin D and lower cholesterol levels. So with less vitamin D, cholesterol

levels might rise. But even though more research is needed, there’s other evidence that shows

how your body takes a whopping in the winter. So much so, that it affects your gene!

One study published in the journal Nature Communications found that around 23% of human

genome expression changes from season to season mostly to boost your immune system.

This time of year is prime cold and flu season, so to fight off infections, your body switches

on certain pro-inflammatory genes.

Your DNA is made up of two strains that wrap around each other in the famous double helix

structure, to get even more compact and tiny, that DNA is wrapped around little proteins

called histones. Think of how thread is wrapped around spool, that’s kind of what histones

look like. When DNA needs to be translated to make proteins, these histones unravel to

let out a little bit of DNA at a time. But which histones unravel when depends on various

influences. In this case, it’s seasonal influences, probably the amount of sunlight.

When the participants went through winter months, no matter what hemisphere they were

in, the lack of sunlight seemed to activate pro-inflammatory genes. And like we know from

other DNews episodes, inflammation, while it can help us fight off some infections,

too much can also harm our health, leading to heart disease, diabetes, or stress related

mental health issues. Which interestingly, the authors think could be another reason

for more cardiovascular deaths in the winter.

But if you live somewhere where there isn’t a winter, your immune system is impacted by

other kinds of seasonal changes. In this study, the researchers found that those who live

in Gambia have seasonal peaks correlated with the rainy season (June to October), when infectious

diseases seem to be more prevalent.

So happy winter to everyone who’s in it! Enjoy your body’s changes. I hope this season

brings you more joy than it brings cardiovascular, psychiatric or inflammatory issues!

Or maybe if you wait long enough, climate change could take away our seasons, starting

with fall. To find out more about the end of autumn, Trace has the scoop in this episode

right here.

So are you a fan of winter? Love to build snowmen in the frozen outdoors? Or are you

a curl up by the fire with a good book kind of person? Tell us your thoughts down below