We're all guilty of it after a long day: sneaking into the kitchen and fixing up a quick Fluffernutter or bowl of instant noodles at 1:30 AM and then tucking yourself into bed, belly slightly engorged, for a deep sleep. Seems harmless enough, right?
Sure, we've all heard about how you might be able to drop a few pounds if you cut off your meal times shortly after dusk. Alright, so maybe a pint of rocky road before hitting the sack isn't the best gift to our waistline (though other studies in recent years say it's not a big deal). But if you're not looking to lose some winter blubber, there's not a whole lot else discouraging a little wee-hours feasting.
Well, actually, there is. There's a reason that the day after a late-night pizza binge, you may find yourself struggling, unable to tabulate the tip for your lunch, squinting at your work spreadsheet, losing your keys twice in six hours. Your midnight meals might be making you just a little bit stupider, says a new study out of University of California, Los Angeles.
It turns out that late-night eating isn't just confusing for your metabolism—it also throws off your circadian rhythm, the oft-cited internal clock that controls your mood, how well you sleep, the hormones your body creates, and basically everything else that makes you feel either "crappy" or "great" when you're going about your day. It's the reason why five minutes after you woke up, you're not as bright-eyed and bushy-tailed as you feel three hours later. And, as it happens, it is also responsible for the dexterity of your learning and memory functions.
The study was conducted on mice by a group of researchers in the psychiatry and biobehavioral sciences department at UCLA, though they are quick to point out that its results have implications for humans as well. The team—led by professor Christopher Colwell—separated mice into two groups, allowing one group to eat normally and only feeding the mice in the second group during the time when they would normally sleep. Both groups were given the same amount of food and slept the same number of hours.
After several weeks, the researchers conducted learning trials on the mice, such as testing their ability to associate a noise with an electric shock. The mice that were on the altered schedule—of eating meals during times when they would normally be asleep—performed significantly worse on the tests, with their learning abilities "severely compromised," in Colwell's words. They exhibited changes in their livers, adrenal glands, and hippocampi, the part of the brain that controls learning and memory, and had increased difficulty identifying new objects in their cages.
Does this mean that a once-in-a-while visit to the kitchen cabinets before bed will leave you unable to remember any of the characters' names on your favorite TV show? Likely not. But over time, disruption of your circadian rhythm—including eating at strange times, or being frequently jet-lagged—can have an impact on your day-to-day behavior and psyche. It can also weaken your immune system and increase your risk of developing type 2 diabetes.
But just as you shouldn't eat a cheeseburger after getting into your pajamas, you also shouldn't work out right before bed. Heavy exercise late at night can also be confusing to your body clock.
Unfortunately, those most affected by this issue are shift workers, such as restaurant workers who may be working "normal" daytime hours on some days and bartending or serving late at night during other parts of the week. Switching it up on the weekends and running around serving gin and tonics until 3 AM can significantly throw off the balance of your mind and body.
But if you can help it, forget about your leftover potstickers and try to sleep off your habit of 24-hour snacking.