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How salt affects your sleep

June 13, 2024 | Valerie Elwell
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"The optimal level of salt intake should be personalized for each person," says Dr. Jaclyn Leong.

Salt is essential for the human body to function properly and to maintain the correct balance of water and minerals. However, studies indicate that too much or too little can interfere with sleep.

“Salt intake and its effects on sleep have been studied since the 1980s,” says Dr. Jaclyn Leong, an internist with the Susan Samueli Integrative Health Institute, part of UCI Health.

One study showed that participants on a sodium-restricted diet of less than 500 milligrams daily — less than a ¼ teaspoon — had higher blood plasma levels of the hormone norepinephrine by the third day, Leong notes.

The participants’ sleep patterns also were disturbed, with a decrease in rapid eye movement (REM) and slow-wave sleep and increased wakefulness. This is likely due to an increase in sympathetic nervous system activity, triggering adrenal activity and a rise in norepinephrine, similar to a fight-or-flight-response. 

“If a person is having symptoms of difficulty sleeping associated with decreased REM and increased wakefulness, this could be a clue indicating salt depletion in their diet,” Leong says.

Conversely, another study found that consuming a high-sodium meal at dinnertime also contributes to sleep disturbances. Participants experienced delays in getting to sleep, multiple awakenings during the night and an average of two to three hours of disturbed sleep.

Why do we need salt?

On the plus side, salt contains sodium, magnesium, potassium and calcium — all necessary for optimal health. Sodium also promotes electrolyte balance and healthy hydration levels.

However, excess sodium intake increases the risk for high blood pressure (hypertension), heart disease and stroke, as well as kidney disease. Eating too much salt also leads to excess thirst, swelling and bloating.

Not consuming enough salt also can lead to digestive issues, muscle cramps, headaches and brain fog.

How much salt is enough?

The U.S. Food and Drug Administration (FDA) reports that on average, Americans consume about 3,400 milligrams of sodium a day, 40% of it from processed foods such as pizza, deli meat sandwiches, canned soups and salty snacks.

Leong says the amount of sodium needed to prevent deficiency is set at 1,500 milligrams or a little more than half a teaspoon a day. To reduce the risk of hypertension and chronic disease, the recommended upper limit is 2,300 milligrams or about one teaspoon.

“Ideally, people should be eating some amount of salt between those two numbers,” she adds.

Salt needs vary

That said, salt intake needs varies from one person to another and also day to day, depending on activity levels and other factors, says Leong.

For example, an athlete's body may need large amounts of sodium to replenish what they lose from exercise and sweating while a sedentary person who consumes the same amount of salt may notice health consequences.

“While low salt diets can be effective for blood pressure control, individuals with high activity levels or minimal co-morbid conditions might become deficient if they are not consuming enough salt.”

She encourages her patients to think about the factors that may affect their body’s sodium needs and to focus on finding a balance.

If you answer “yes” to the following questions and you are very active, you may need more salt in your diet, Leong says.

  • Do you sweat during activities or exercise?
  • Are you exposed to heat?
  • Do you have muscle cramping?
  • Do you experience insomnia or reduced sleep?

Answering “yes” to these questions may indicate a need to dial back your salt intake.

  • Do you have high blood pressure?
  • Are you unusually thirsty?
  • Do you get headaches?
  • Are your hands and feet swollen?
  • Do you experience puffiness or bloating?
  • Do you eat mostly processed foods?

Striking the right balance

The key to understanding whether you are eating enough or too much salt is monitoring your daily sodium intake.

“For example, someone who cooks at home with fresh ingredients and does not add any salt to their diet, could possibly be under salting and getting less than 500 milligrams daily,” Leong says. “Whereas someone who eats out for every meal is likely getting far more than the recommended amount of sodium.”

In general, anything processed is likely to have a high salt content so removing or minimizing processed foods in the diet not only limits salt intake, it also lowers your risk for many health conditions.  

“There can be hidden salt in foods that you may not necessarily think are processed,” Leong explains. “For example, canned soup can have at least 500 milligrams of sodium in a single cup.”

She recommends preparing meals using fresh, whole foods and adding no more salt than the recommended daily amount — about a teaspoon — to ensure good health. 

Ultimately, when it comes to salt, moderation and balancing your intake leads to better health — and better sleep!

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