Even though many of us wake up in the middle of the night thirsty and/or needing a bathroom, few of us decide to stay awake to eat another dinner. To be sure, we may munch on a graham cracker, nibble on some leftover pie, or drink a glass of milk with some cookies. But with the exception of a category of people called night eaters, we rarely are hungry enough to eat a full meal, even though it has been hours since we last ate.
The almost physical inability to put much food in our stomachs is evident with the lackluster appetite we may approach breakfast served on a transatlantic flight at 2 or 3 in the morning. We are awake, more or less, but our stomachs are not. Conversely, some of us can tell time by the mid-day and early evening rumbles in our stomach signaling, “Time to eat!” Why are we hungry for lunch or dinner five or fewer hours since the previous meal, and yet not hungry in the middle of the night, eight or nine hours after we had dinner? By the time we leave infancy, most of us are unlikely to wake up for a 2 A.M. feeding.
A hormone, secreted by the stomach but acting on the brain, may be the answer. Ghrelin (rhythms with Mary Ellen) seems to initiate eating at certain times over a 24-hour cycle, but not at other times. Although it seems as if we eat by the clock as in, “It is noon so I must be hungry,” this is apparently not the case (at least not in a research situation). About seven years ago, in a study published in the American Journal of Physiology by D.E. Cummings and colleagues, ghrelin levels were measured in volunteers whenever they started eating a meal. The researchers found that when the volunteers were most hungry, right before they started a meal, their ghrelin levels were high. After eating, ghrelin levels in the blood decreased and, as time passed, slowly began to rise again. Five or six hours after the previous meal, hunger and ghrelin levels again were high, and the subjects started on their next meal.
So why are we all not in the kitchen at 1 or 2 A.M. looking for something to eat, 6 or 7 hours after dinner? Most of us are asleep and if awakened would probably turn down a sandwich or some scrambled eggs. We are not hungry. The reason? According to research reported in the European Journal of Endocrinology by Natalucci, et al, the level of the hunger hormone is lowest between midnight and 7 A.M.
But some people do wake up every night hungry enough to eat more than a few crackers and drink some milk. These so-called night eaters may actually consume as many calories as the rest of us eat at dinnertime. They are not eating in order to fall back asleep but because they are hungry. It is unclear if they wake up because they are hungry or notice how hungry they are when they wake up for other reasons such as noise or a need to go to the bathroom. Hungry they are, however, and apparently because night eaters have an abnormally high level of ghrelin in the blood between midnight and morning. It is as if this hormone is out of sync with the other hormones, primarily melatonin, that should be keeping them asleep, not microwaving pizza or defrosting a steak in the middle of the night.
No one quite knows what to do about the high levels of the hunger hormone in the wee hours of the morning. Researchers acknowledge that the rise of gherlin is delayed, so that instead of increasing late in the afternoon/early in the evening, when we normally would be eating our evening meal, it seems to peak five or six hours later. One thought is to expose night eaters to early morning light therapy similar to the lightboxes used by people with SAD (Seasonal Affective Disorder). According to a paper by Goel N. Stunkard and others in the Journal of Biological Rhythms, night eaters who have been exposed to early morning light respond by eating at normal meal times and will decrease their nightly food consumption. Maybe the light changes the rhythm of ghrelin release so that it approximates the normal sleep/wake cycle. Or perhaps waking people up early to sit in front of a lightbox gets them to eat breakfast early in the morning (although it is hard to believe they will be hungry) and this sets up a normal ghrelin prior to lunch and then dinner time.
Or, perhaps, the answer is to move to Spain where everyone seems to eat supper after the late show.
It’s 2 a.m. You’ve been asleep for a few hours, but, suddenly, you wake up hungry and desperate for a snack (at least), so you head to the kitchen. Nearly everyone is familiar with this scenario as a once-in-a-while thing, but what about when this is what almost every night looks like?
If getting out of bed to eat has become a habit for you and you’re not sure why that might be, hello and welcome—especially if you’re reading this article on your phone in the kitchen with a fork in the other hand. Let’s see if any of the very many reasons for sleep-interrupting eating feel familiar to you—and what you can do about it.
Typically, our bodies know that sleeping and eating don’t go hand in hand. When we fall asleep, our bodies produce higher levels of leptin, a hormone that suppresses appetite, and when we wake up, production of the hormone ghrelin ramps up and tells our body it’s time to eat.
If your middle-of-the-night snacking is a random one-off, it’s probably because you did something different that day—maybe you had a huge workout and burned through a lot of caloric energy or your regular sleep cycle was disrupted by drinking too much alcohol or pulling an all-nighter. Anything that generally messes with your sleep schedule can also cause you to wake up hungry in the middle of the night.
If you find yourself waking up hungry during the night at least a couple times a week, there’s probably something else going on. Scientists say this pattern of eating, called nocturnal ingestions, is much more common than you’d think. The highest rates are seen in people with obesity, substance use issues, and psychiatric conditions, and estimates suggest about 1.5 percent of the general population suffers from severe, chronic nocturnal ingestions that can be classified as a disorder called night eating syndrome.
The bulk of nocturnal eating episodes is probably massively underreported, experts say, so the true prevalence is likely much, much higher. On top of that, nighttime eating behaviors are generally understudied at the moment, as they’re not exactly the National Institutes of Health’s main priority right now. While scientists have gleaned some valuable insights about why we wake up in the night ready to eat (hint: it’s probably stress), progress with newer studies has been slow—but here’s what experts do know about nocturnal ingestions.
Nicole Avena, a research neuroscientist who focuses on nutrition, diet, and addiction, said patterns of nocturnal ingestion tends to occur when people start fasting or otherwise dramatically reduce their food intake. “They bring their calorie intake down so low during the day, and then they end up having their whole circadian rhythm thrown off,” said Avena. “They can’t sustain themselves through the night, so their body just naturally awakens.” The nocturnal cravings typically subside once their body adjusts to the diet.
There’s also a notable crossover between nighttime eaters and people with diagnosed eating disorders. One study found that 51 percent of people with bulimia and about 35 percent of people with anorexia are prone to nocturnal ingestions. The reason, according to Allison, is that their basic “energy needs aren’t being met.” In addition, people’s thinking is more flexible during the night, so where someone might be concerned about what they consume during the day, those inhibitions tend to loosen up when grogginess sets in overnight.
But Kelly Allison, a professor of psychology in psychiatry at the Perelman School of Medicine at the University of Pennsylvania, says it’s most often not physical hunger that drives someone to wake up ravenous in the middle of the night. Nighttime eating can also sometimes be traced back to a stressful event. (Like, say, a global pandemic.) Through her research, Allison has found that about three-fourths of people who regularly engage in nocturnal ingestions experienced some kind of stressful event that threw off their sleep schedule and made midnight snacking seem enticing.
Other evidence suggests people diagnosed with depression and anxiety are more prone to nocturnal eating. “Any type of mood disorder can put people at risk for developing this type of night awakening and eating,” said Avena.
Emotional eating can be a powerful stress-reliever, at least in the short-term. Instead of sitting in bed mulling over anxiety-provoking thoughts that disrupt sleep, people often turn to food as a sleep aid. “It can certainly slow down your thought processes—if your body is digesting food, then maybe you’re distracted from the anxiety that’s keeping you awake,” Allison said. “It is, unfortunately, an effective way to deflect those kinds of thoughts and focus on the eating.” Once people start using food to get back to sleep, Allison said, they may get sucked into a cycle in which they routinely feel like they won’t be able to fall back asleep unless they eat, and their body also starts to expect food on that schedule.
If you’re like, OK—but I’m eating enough during the day and generally feel fine, and I’m still waking up to eat, you’re not alone. According to Allison, about a fourth of people who wake up hungry aren’t able to identify a root cause. It could be a genetic predisposition, said Allison, but researchers haven’t yet identified a specific gene that’s responsible. If someone has a family member who also wakes up and eats, that’s a clue it could be genetic, said Allison.
While sporadically snacking in the wee hours isn’t going to do much harm, consistently doing so can lead to a host of health issues. Nocturnal snackers often restrict how much they eat the next morning. Some overexercise. Their sleep is disturbed and they’re more likely to stir during the night, contributing to low moods that generally worsen throughout the next day, explained Allison—which, in itself, can help perpetuate patterns of late-night eating. Frequent nighttime eating can also impair cholesterol and insulin levels over time.
There are interventions that can help break the cycle of taking your meals in the middle of the night. Allison suggests substituting eating with another activity—playing some music, meditating, reading a book, or watching TV reruns. In extreme cases, experts recommend locking food cabinets during sleeping hours.
Trying to avoid waking up isn’t usually a person’s best bet, as over-the-counter drugs like melatonin could actually do more harm than good: They may help people fall asleep, but they aren’t great at keeping people asleep. In fact, with melatonin, people may wake up even groggier during the night and have even less control over whether they choose to eat, explained Allison.
If none of that is enough to keep you away from your refrigerator when you’d rather be resting, your best bet is to ask a medical professional what the reason could be. “If you’re having this happen to you, it’s a very good idea to consult with your physician because there could be some other underlying cause that we’re just not aware of,” Avena said. Waking up to eat isn’t a huge deal on its own if it doesn’t happen that frequently—but if you’re finding that a regular mealtime for you is 4 in the morning, it’s time to check in with your doctor.
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