Late night snacking packs on the pounds. And the wrinkles.

Add sun damage to the consequences of nocturnal noshing.

Add sun damage to the consequences of nocturnal noshing.

(Credit: iStock/Getty Images)

It's night time. The sun is shining its grace on some other continent. You stand silhouetted by only by the fridge light while you work your way through the final slice of congealed cheese and rubbery dough that was last night's take out pizza, surely inviting the chub fairy to pay you a visit once you crawl back into bed. But tighter PJs won't be the only price you pay — science now warns you could be inviting sun damage too.

Yes, you may have one more reason to worry about the sun's potentially damaging rays: the midnight snack.

It seems like a bizarro claim but new research out of the O'Donnell Brain Institute and UC Irvine showed that abnormal meal times confound the biological clock of our largest organ (it's our skin, if your biology is rusty). The study showed conclusively that feeding mice at unnatural times reduced the effectiveness of a crucial enzyme in their skin that normally provides daytime protection from hazardous ultraviolet solar radiation.    

Mice are nocturnal rodents, which is why the best time to meet one is when you're stuffing your face in your kitchen at midnight. But when mice were fed during the day, they took a much harder hit of skin damage when exposed to ultraviolet light. One reason for their susceptibility is that XPA, an enzyme that usually repairs sun blasted skin, became considerably less active during daylight hours when it was needed most. Mice that ate like civilized rodents at reasonable nighttime hours stayed safer under UV rays. No altered XPA cycles meant a more efficient natural skin shield. The data underlines what we've known for awhile: bodies run best on a schedule.   

If you're partly assuaged that you aren't a mouse, consider that Dr. Joseph S. Takahashi, Chairman of Neuroscience at O'Donnell, thinks the findings are quite likely to apply to humans too. Folks who tuck in well after the sun goes down may be leaving themselves more vulnerable to sunburn — something we know translates to unwelcome lasting effects like overly weathered skin. So, Spielberg was kind of right about nighttime chow downs. They'll turn you from a cute mogwai to a crusty gremlin in a bite. You heard it/read it here first. Gremlins is science.

If vanity won't curb your nocturnal snack lust, remember that the A-lister baddie, cancer, also creeps up on us as a long-term consequence of sun damage. Takahashi admits more research is needed to understand the full implications for humans but is adamant that the discovery is remarkable. "This finding is surprising. I did not think the skin was paying attention to when we are eating."

The study isn't the first to make strong links between the skin and our circadian rhythms. Back in 1998 we discovered that our sleep cycles could be rejigged by shining UV light on the back of our knees. Eyeballs didn't need to factor in at all as light receptors. But this new feeding/body rhythm link to the skin is entirely novel. Still, past findings have shown that mealtimes do have an affect on the regular metabolic cycles of the liver. On the off chance you're making a top five list, it's our second largest organ (then brain, then lungs, then heart). Your pineal gland in your coconut is the smallest. Go forth and impress your pals on trivia night.  

"It is likely that if you have a normal eating schedule, then you will be better protected from UV during the daytime," says Takahashi. "If you have an abnormal eating schedule, that could cause a harmful shift in your skin clock, like it did in the mouse." The takeaway is clear: honour that skin clock — eat during the day.   

If you think you're likely to maintain the normal resolve of a regular human and hit up some street meat on your next late night stroll home from the bar, maybe slather on the SPF 60 when you wake up. Or before bed. Do protect that mega organ and save your skin. A new one will be tough to come by.  


Marc Beaulieu is a writer, producer and host of the live Q&A show guyQ LIVE @AskMen