This Is Why You Can't Sleep on a Low-Carb Diet

Low-carb diets and insomnia are linked, but there are a few things you can do to get better sleep.
Image Credit: tommaso79/iStock/GettyImages

Sure, a low-carb diet might help jumpstart your weight loss, but shunning starchy foods can affect more than your calorie count — it could also keep you up at night. Yep, studies show there's a link between eating low-carb and insomnia.

That's not ideal, because getting enough shut-eye is essential for losing weight. Read on for the breakdown on the sleep-carb connection and what you can do about it.


Low-Carb Insomnia

A low-carb diet limits carbohydrates found in grains, starchy vegetables and fruit, and focuses on foods high in protein and fat, according to the Mayo Clinic. This way of eating causes the body to burn stored fat for energy, which can lead to weight loss.

Unfortunately, the low-carb diet that's making the number on your scale go down in the morning can actually keep you up at night.

A study published February 2013 in the Journal of Epidemiology concluded there was a correlation between carbohydrates and sleep. A diet that involved less than 50 percent of caloric intake from carbs was slightly linked to difficulty in staying asleep during the night in men.


Similarly, a February 2015 study in the Journal of Sleep Research showed that some people with sleep apnea and insomnia reported a lower carb intake than those who didn't have sleep disorders.It's worth noting, though, that this was only found in people who were obese and identified as male.

So, what gives? Sleep specialist Michael Breus, PhD, says a sudden shift from carbs to protein could explain why some people have sleep troubles. Levels of the amino acid tryptophan in the brain are increased with carb consumption, he explains. The tryptophan converts to serotonin (the "happiness hormone"), which is needed to produce melatonin — the sleep hormone.


Now protein, on the other hand, increases levels of tyrosine, an amino acid that causes the production of epinephrine (adrenaline) and norepinephrine. Those will kick your body into high gear.

So, in other words, if you're reducing serotonin by reducing carbs while elevating the "alertness-promoting" chemicals with more protein, be prepared for some late nights.

And these changes could just happen overnight, so to speak.

"The impact of diet on sleep seems to occur relatively quickly," says Marie-Pierre St-Onge, PhD, associate professor of nutritional medicine and director of the Sleep Center of Excellence at Columbia University Irving Medical Center. "In a study we published in 2016, we showed that a change in intakes from one day to the next had an influence on sleep quality that night. In that study, eating more fiber, less refined carbohydrates/sugar and less saturated fat was associated with overall better sleep quality."


Related Reading

Carb Quality vs. Quantity

So, while eating fewer carbs has been linked to shoddier sleep, the real culprit may be the quality of the foods you're choosing, St-Onge says.

"I think it's more important to talk about quality of macronutrients than quantity, whether we're talking about fats or carbohydrates," St-Onge says. "If you choose to go low-carb, you should make sure that the carbohydrates you consume are complex/not refined. Those should come from whole grains, fruits, vegetables and legumes. Fat should be unsaturated, from plant-based oils rather than tropical oils and animal products."

Anything made with white flour (refined carbs) should be nixed, per the Harvard T.H. Chan School of Public Health. Soda, candy and a host of processed foods that contain added sugar and corn syrup are red-flagged too, according to the United States Department of Agriculture.

Indeed, the Mediterranean diet — a plan that emphasizes healthy carbohydrates like fruits, vegetables and whole grains — is associated with a lower risk of insomnia. A study published November 2018 in Sleep found that those who closely followed the diet experienced fewer symptoms of insomnia and a longer sleep duration.

Similarly, an August 2014 study in the Journal of Occupational Health found a high intake of refined carbohydrates, such as noodles and sweets, was linked with poor sleep quality, while a high consumption of vegetables and fish was connected to better sleep quality.

Related Reading

Sleep Solutions

So, what's a person to do if they want to continue low-carbing but really need to get back to sleep?

Other than choosing those healthy carbs, Shanna Levine, MD, owner of Goals Healthcare, gives some helpful suggestions:

1. Practice good sleep hygiene.​ The Sleep Foundation defines sleep hygiene as creating a consistent nightly routine filled with healthy habits. This might include budgeting the half hour before bedtime for calming activities like light stretching or reading and unplugging from electronics.

2. Eat your allotted carbohydrates in your last meal of the day​, as they should help promote sleep. (Just keep in mind that you should aim to eat at least three hours before bedtime for digestion purposes.)

3. Treat the bed and bedroom as a sacred place only for sleep.​ That means no working from bed, eating in bed or lounging there while you watch Netflix. (Think: calmness and tranquility!)

4. Up your exercise.​ Being more physically active during the day could help you nod off better at night. Just don't work out within several hours of sleep, as it might have the opposite effect.

Of course, if you're really struggling with sleep and none of these suggestions work, make an appointment with your regular physician or a sleep specialist so you can finally get the shut-eye your body and brain need.

Related Reading