I used to wonder if opening the fridge at night and peering around was an abnormal habit of mine, or maybe even a muscle-memory thing. Googling “Why do I get hungry at night?” reveals that I’m not alone: Variations of that same question appear to have been asked on every internet forum known to mankind. Like most things, the phenomenon can be explained by science.

Cause: Totally Natural Circadian Rhythms

As it turns out, it’s completely normal to experience intensified hunger at night. An oft-cited study found that the body’s internal clock, the circadian system, increases hunger and cravings for sweet, starchy, and salty foods in the evenings — which certainly corresponds to the food choices that my cohorts and I make in the wee hours. (Praise be to my neighborhood’s 24-hour taco trucks and ice-cream shop.) Participants in the study were least hungry at 8 a.m. and most hungry at 8 p.m., a cycle regulated by the circadian system. In the evenings, our bodies naturally favor larger meals for food storage in preparation for the “fasting period” brought on by sleep — an eating pattern followed by sumo wrestlers to gain weight. “While this may have been valuable throughout evolution, nowadays it is likely to contribute to the national epidemic of obesity,” cautions lead researcher Dr. Steve Shea. (Thanks a lot, ancestors!)

Hormones Might Explain It, For Some

Studies have shed light on something called Night Eating Syndrome (NES), which affects an estimated 1.5% of the general population. Those with NES don’t each much during the day, consuming a significant portion of their calories under cover of night instead. While it’s unclear what exactly is responsible for the syndrome, a prevailing theory involves an imbalance in the hormones that regulate sleep, appetite, or mood. According to Columbia University’s Go Ask Alice!, “NES may be your body’s attempt to compensate for improper levels of a hormone called serotonin,” which regulates circadian rhythms. And the foods we crave at night — high-carb, high-cal snacks — turn out to replenish serotonin, aka “the mood hormone.” (That explains why a grilled cheese is 100% more satisfying at 1 a.m. than at any other time, amirite?)

Also a Thing: Ravenous Genes

Your genetic makeup also can lead to midnight munchies. In 2014, scientists discovered a pair of genes, PER1 and PER2, that normally keep eating and sleep habits in sync. When a mutation is present in PER1, however, all-powerful night-time cravings descend upon us. In tests, scientists observed mice with a mutated PER1 gene waking up and seeking out food when they should’ve been fast asleep. That doesn’t necessarily mean that mutation carriers will feast uncontrollably at night, though. According to the Salk Institute for Biological Studies’ newswire, “When [the] team restricted access to food, providing it only at the mice’s normal meal times, they found that even with a genetic mutation in PER1, mice could maintain a normal weight.” In other words, maybe limit your access to late-night food stashes (and taco carts).

Rest assured that it’s not just you — night-time cravings are a universal experience. And they don’t necessarily mean bad things for your health. It’s okay to indulge at night, so long as you maintain healthy eating habits during the day. An easy way to keep yourself in check is to allot a small handful of calories to consume before bedtime. Snacks like Nature Valley Granola Cups — whole-grain oat granola cups filled with peanut butter and dipped in chocolatey goodness — make for an ideal night-time indulgence: They’re sweet, crunchy, and only 200 calories per serving (for two whole cups, y’all). Reason to never go to bed hungry — or in a food coma — again.

Angela Wang is a Senior Writer for Studio@Gizmodo.

This post is a sponsored collaboration between Nature Valley and Studio@Gizmodo.