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Midnight snacks might be shortening your life

The longer you live, the more snacks you can have, but only during the daytime.

By Cassidy Ward
Man having snack in front of the refrigerator at night.

Dracula has a lot going for him. He’s a property owner, strolls around in sweet capes, and has Bela Lugosi’s charm and good looks. His diet, however, leaves a little to be desired. A deadly allergy to sunlight means that vampires have to sleep during the day — in uncomfortable looking coffins, no less — and are limited to the nighttime to eat. It’s a wonder, then, that they’re so long lived. Because, as it turns out, midnight snacking might have pretty serious negative effects for your health.

A recent study carried out by Carla Green from the Department of Neuroscience at the University of Texas Southwestern Medical Center, and colleagues, looked at the impact of restrictive diets on longevity and found a compelling correlation between circadian rhythms and how long an individual lives. Their findings were published in the journal Science.

Prior studies in mice revealed that calorie restriction has a positive impact on longevity, resulting in life roughly 10% longer than peers who were allowed to eat whenever the urge struck them. In looking at the data, however, scientists realized there might be some fuzziness in the numbers. Many of those studies relied on feeding mice on Monday, Wednesday, and Friday mornings, with a double dose on Fridays to get them through the weekend. While that succeeded in restricting calorie intake, it also introduced significant periods of fasting, followed by rapid consumption in the mornings, when mice aren’t usually active.

“What you’re really getting is a narrow spike of a lot of food at the wrong time of the day and then a big fast. That caught our attention and we thought it would be interesting to see if it was really the caloric restriction or something about the timing or fasting interval causing the effect,” Green told SYFY WIRE.

Previous studies fed mice in that way, owing to the logistical complications which come with a human researcher manually feeding hundreds of mice on a regular schedule. To get around that limitation, the new study developed automated feeders which delivered food to mice at night, when they are naturally active. Feeding them only during the period of hours when they’re most active, coupled with caloric restriction, resulted in mice which lived 35% longer than those who were free to eat whenever they wanted, adding roughly nine months to their usual two-year lifespan.

Woodmouse eating breakfast

“We saw big changes in things like inflammatory signatures and other metabolic pathways,” Green said. “During normal aging, in wild-type mice on adlib diets, they get reduced [circadian] rhythms, reduced metabolic health, and increased inflammation. When we put them on timed diets where they’re eating only during their normal active phase, we see an improvement of those pathways back to a younger age.”

In short, inflammation decreased and metabolic pathways increased. In many ways, the bodies of older mice appeared as though they were younger than they actually where, when compared with a control group.

Studies suggest that the opposite effect is also in place. Eating outside of your body’s natural active period can have significant detrimental effects on overall health which can contribute to a reduced lifespan or lower quality of life. Studies also involving mice, during which they were fed high-fat diets, revealed that those who ate only during their active period suffered few consequences while those who snacked during rest periods experienced fatty liver disease and problems with glucose regulation.

Mice aren’t a perfect model for humans so it’s unclear how much of this translates to our own bodies, but it’s likely that our own metabolism as it relates to circadian rhythms works more or less the same. While the phases of our rhythms are reversed — humans being diurnal while mice are nocturnal — the overall rhythm and the pathways they control are the same. All of which means your midnight snacks might be doing you more harm than you realize.

Cutting the midnight foraging out of your routine and limiting your eating schedule only to the hours when you’re awake and active could push the specter of death further down the road. Whether or not losing the 2:00 AM peanut butter and jellies is worth it is, of course, a personal decision. They are tasty.