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BY JULIA LAYTON
 |
| Wait -- could slathering on the sunscreen actually make you less healthy? |
With
the dire warnings in mind, most of us apply sunscreen every day and seek out
shade when we're outdoors, lest our skin come into contact with the sun's
harmful UV rays.
As it turns out, there's another
side to the story. Sun exposure isn't all bad. In fact, it's mostly good.
That's right: Sun exposure is good for you. After decades of avoiding it,
researchers are finding that we may have been doing more harm than good.
It's a shock to the system, for
sure, but the evidence is substantial.
A
chronic lack of sun exposure has been linked to fertility problems, several
forms of cancer, general poor health and varying degrees of depression.
 |
Lack of sunlight has a profound effect
on most people's mood. |
The form of depression most
often associated with variations in sunlight is seasonal
affective
disorder (SAD).
disorder (SAD).
The
disorder runs in cycles of depression and wellness that follow the seasons --
more specifically, the availability of sunlight.
Someone
with SAD might feel perfectly fine in spring and summer, and then experience a
severe downturn in mood when fall hits.
They'll
stay that way through the winter, until the sun comes out again in full force.
SAD
is particularly prevalent in parts of the world with little winter daylight and/or
extended overcast periods, like Alaska or the U.S. Northwest.
In
this article, we'll find out why sunlight exposure can affect your emotional
well-being and how you can safely use the sun to benefit your mood.
As it turns out, humans aren't
quite as removed from their natural instincts as some believe.
Ups and Downs of Light
Most
animals are sensitive to light. Their biological processes are profoundly
affected, sometimes even controlled, by the cycles of sunlight and darkness
that characterize day and night.
These
relationships are called circadian
rhythms, and they help maintain cycles like sleep and wakefulness and are
connected with seasonal fertility in "lower" animals.
In humans, the connection
between light and biology is somewhat looser.
People
don't typically mate seasonally, for instance -- although conception peaks in
Finland in the summer months, when the sun shines for up to 20 hours a day, so
there's still a connection there [source: Brody].
And
as for sleep patterns, while most people sleep at night and are active in the
day, there are plenty of people who reverse that to work the graveyard shift.
But
evidence shows that those graveyard shifters may be suffering from the reversal
in unexpected ways.
One
area where humans may not be able to escape the sun's biological effects is on
their moods. It all comes down to a complex relationship among sunlight,
melatonin and serotonin that we're only just starting to understand.
Melatonin is a hormone that
controls sleep, and serotonin in a neurotransmitter that is tied to states of
wakefulness and being in a "good mood."
Serotonin
is the chemical targeted by a class of anti-depressants called SSRIs, which
keep higher levels of serotonin in the bloodstream to help elevate mood.
The web connecting sunlight,
melatonin and serotonin goes something like this: When the sun comes up again,
and sunlight hits the optic nerve, some of that light is sent to the gland in
the brain in charge of melatonin.
In
response, melatonin secretion decreases. When the sun goes down, the body
increases its secretion of melatonin.
At the same time, when the body
perceives sunlight, serotonin levels increase. And the more sunlight the human
body is exposed to, the more serotonin the brain produces [source: ScienceBlog].
So
in effect, melatonin and serotonin have an inverse-proportional relationship
that is guided by the body's perception of sunlight. The overall effect is
"downtime" at night and "uptime" during the day.
There's another factor involved
in sunlight's affect on mood, though: vitamin D.
The
body actually creates its supply of vitamin D from the sun's ultraviolet rays
hitting the skin, and high levels of vitamin help the body maintain high levels
of serotonin [source: Collinge].
So what does this mean for the
daily sunscreen routine? Are we bringing on sadness by protecting our skin from
UV light?
Sunblock Buzz Kill
When
health-conscious people apply sunscreen regularly to all exposed skin before
heading outside, they may actually be doing more harm than good.
People who suffer from seasonal
affective disorder are most likely missing out on the visible part of the sun's
light spectrum.
That's
the part that communicates with the brain via the eye, affecting melatonin and
serotonin rhythms. In those cases, exposure to full-spectrum sunlight -- even
artificial sunlight -- can help to elevate mood [source: Brody].
That's
the basis of phototherapy for depressed patients with SAD. Sunscreen isn't
necessarily a problem in that regard.
But
a lack of exposure to the ultraviolet part of the spectrum -- the light rays
that are blocked by sunblock on the skin -- could be helping to keep the
depression cycle in business.
If
you're never in the sun without UV-blocking sunscreen, your body probably isn't
producing enough vitamin D.
And
research shows that loading up on vitamin-D-producing sun exposure in bright
summer months can help maintain high serotonin levels through dark winter
months [source: Collinge].
And what if you don't suffer
from severe winter depression?
Does
that mean you should feel fine about getting all of your light exposure from
incandescent or fluorescent bulbs?
Probably
not. Too much exposure to limited-spectrum indoor lighting, and the related
under exposure to full-spectrum light, has been connected with problems like
fatigue, reduced immune function and possibly fertility issues [source: Brody].
What's
more, vitamin D deficiency may increase your risk of getting certain types of
cancers, including prostate, colon and, believe it or not, skin [source: USA Today].
So do we throw out everything we
know about the evils of sunlight and go bake in the sun to our hearts' content?
As with everything else,
moderation is key.
First,
to help your circadian rhythms stay in tune, get all of the sunscreen-protected
sunlight you want, and make sure you open the blinds when you're stuck inside.
To
keep up your supply of vitamin D, aim for about 15 minutes of unprotected sun
exposure three times a week [source: USA Today].
For more information on
sunlight, circadian rhythms, happiness and related topics, look over the links
below.
Julia
Layton has a B.A. in English Literature from Duke University and a Master
of Fine Arts in Creative Writing-Poetry from the University of Miami. When
she’s not at the Writing Center, she works as a freelance writer and editor;
her writing is published on web sites like HowStuffWorks, The Learning Channel,
and Forbes. In her free time, Julia cooks, reads, worries, makes jewelry, and
raises a child.
https://science.howstuffworks.com/life/inside-the-mind/emotions/sun-happiness.htm
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