You’ve barely started your day, but for some reason you just can’t shake your nerves. As the minutes tick by, you find you’re having trouble focusing and—ugh—start to feel a headache creeping in. Did you drink too much caffeine, you wonder? Or was it the poor night of sleep you had last night? Or something else entirely—perhaps something more serious?
This mid-morning struggle can be a pretty common experience—and, believe it or not, your seemingly unrelated symptoms may have a surprising (and luckily very treatable) culprit: low blood sugar.
Like that friend who always answers text messages 72 hours after you send them, low blood sugar can be hard to pin down. Without a blood glucose monitor, there’s no way to know exactly how high or low your numbers have spiked or dropped. Still, that doesn’t mean you can’t be on the watch for symptoms that indicate your body’s glucose reserves have slipped.
Here are five surprisingly common signs of low blood sugar, plus what to do when they crop up.
“Hanger”—the general grumpiness you feel while hungry—may be a made-up word, but the phenomenon is totally real. (If you’ve ever snapped at a co-worker and immediately regretted it right before lunchtime, you can attest.) There’s actually scientific evidence that not eating can put you in a bad mood! Research from 2022 followed 64 subjects, observing their emotions at five points each day. When the subjects felt hungry, they were more likely to also feel anger and irritability and less likely to experience pleasure.
Granted, nobody feels chipper when their belly is empty, but the rumbles may not be the only cause of hanger; low blood sugar levels are also likely involved. “The main source of energy for the brain is glucose,” explains dietitian and certified diabetes educator Erin Palinski-Wade, R.D., C.D.C.E.S., author of 2-Day Diabetes Diet. “When blood sugar dips, this lowers the energy available to the brain, which can have a direct impact on mood, concentration, and even stress levels.” So before you take out your aggression on an unsuspecting colleague or family member, consider taking out a snack.
2. Nervousness and Anxiety
You might chalk it up to your large afternoon latte, but feeling jittery, nervous, or anxious can actually be an indicator that your blood sugar is off-kilter. As far back as the 1980s, researchers have known that there’s a connection between nervous feelings and blood glucose fluctuations. In fact, one case study from 2016 even suggests that generalized anxiety disorder could be improved with a lower glycemic (a.k.a. more blood sugar-balancing) diet.
So why do decreased sugars mean increased anxiety? “When your blood sugar starts to drop, your body looks to bring it up to a functional level,” says naturopath Louise Westra, M.S., N.D. “To ensure that happens, your body pumps out epinephrine (also called adrenaline), one of your ‘fight or flight’ hormones, which instructs your liver to make more glucose.”
Thing is, the release of this hormone prompts physical symptoms like a more rapid heart rate and sweaty palms, which can make you feel on edge. “If things don’t get regulated pretty quickly, your body adds the additional response of secreting cortisol, another stress hormone,” says Westra. “When you put adrenaline and cortisol together, you’ve got a recipe for even more heightened symptoms.” Definitely worth checking in with yourself about the last time you ate (and what you munched on) the next time your nerves kick up for no apparent reason.
In addition to nervousness, the ebb and flow of the hormones triggered by low blood sugar can bestow yet another unpleasant gift: a headache, which is a common hormonal byproduct of insufficient glucose. “As these hormone levels shift, it can cause the blood vessels in the brain to dilate, triggering a headache,” Palinski-Wade explains. Get this: According to 2022 research, impaired glucose metabolism, reduced insulin sensitivity, and fluctuation of blood glucose have all been linked with an increased risk of migraines.
Read More: 8 Reasons Why You’re Getting Bad Headaches
Whereas migraines can be debilitating and often affect only one side of the head, your standard hypoglycemic headache can also feel like a run-of-the-mill tension headache. “Typically, a headache caused by a dip in blood sugar would be felt as a dull ache near the temples, but it can run across the forehead as well,” says Palinski-Wade.
4. Brain Fog
Brain fog is one of those symptoms that’s tough to describe—and sometimes even tougher to find a cause for. One possible explanation for the sensation of moving through a mental cloud? You guessed it: low blood sugar.
“Unlike muscles or other organs, the brain can literally only use carbohydrates for fuel,” explains Dr. Alexa Neynaber, N.M.D., I.F.M.C.P., of Virasoap Natural Medicine. “You need a certain amount of blood glucose for the brain to work!” Typically, after you eat something containing carbohydrates, your body breaks them down and releases the basic sugars into your bloodstream to circulate as energy for your various organs, including (of course!) your brain, she says. When that supply of sugar dips, well, you hit the proverbial wall.
When trying to identify the cause of endless yawning, don’t discount scanty blood sugar levels. Just as a glucose deficiency means less energy for your brain, it also means less energy for the rest of your body, leaving you feeling stuck in a slower gear. While you may notice the sloth-like energy creep in after going too long without a nourishing meal, “you’ll feel especially drained when the feedback loop is chronic, meaning you’re consuming simple carbohydrates often, causing a swing back and forth between rapid hypo- and hyperglycemia,” Neynaber says. Basically, the more you rely on simple carb- and sugar-filled foods, the more likely you are to experience the energy zap in the hours that follow.
Keeping Your Blood Sugar Stable
The surest way to avoid dreaded low blood sugar symptoms is to keep your glucose from dipping in the first place. If you know you’re prone to bouts of hypoglycemia, it’s smart to get ahead of the curve by taking preventative action, which may be as simple as eating balanced meals on a more regular schedule.
“The best strategy to prevent blood sugar from dropping is to eat balanced meals and snacks every three to four hours,” suggests Palinski-Wade. “Balance your plate with a source of fiber-rich, slow-digesting carbohydrates, plus lean protein and healthy fats to promote stable blood sugar levels throughout the day.”
Neynaber agrees that a balanced plate truly is your best bet. “By having a balanced, whole food-based diet that supplies fiber, fats, and proteins with carbohydrates, you will slow gastric [a.k.a. stomach] emptying and intestinal absorption of sugars,” she says. In addition to helping you avoid the short-term struggles of dipping blood sugar, it also prevents long-term issues like elevated insulin levels and insulin resistance.
At mealtime, balance might look like a salmon filet over brown rice with some roasted veggies, a leafy green salad with chicken and almonds, or a quinoa bowl with sweet potato and black beans. As far as snacks go, try whole-wheat crackers with hummus, Greek yogurt with berries, or trail mix made with nuts and dried fruits.
What To Do When Your Blood Sugar Has Dipped
If you’ve pushed off eating for too long and are now feeling the tell-tale signs of low blood sugar, rather than go down in a blaze of jitters, it’s time to take action. “When blood sugar drops, the best thing you can do is eat a food containing carbohydrates,” says Palinski-Wade. “For those who have mild drops in blood sugar, eating a complex carbohydrate such as whole-grain bread or whole fruit can help to increase blood sugar back to normal levels.” (People with diabetes should follow their doctor’s instructions for managing blood sugar levels.)
As soon as you’re feeling stabilized, munch on something that’ll keep you there. “Once blood sugar is back to normal, eating a balanced snack or meal with protein, fat, and carbohydrate can help to prevent blood sugar from dropping again,” Palinski-Wade offers.