Insomnia, leg cramps at night? You may be low on magnesium

When your eyelid starts twitching, the advice you are most likely to hear is "eat a banana."

But a banana may not be the best choice in that situation. If magnesium deficiency is the culprit, a handful of almonds would serve you better.

Bananas are rich in potassium, vitamin B6 and carbohydrates, but their magnesium content is only average. According to nutritional data from the Ministry of Food and Drug Safety, 100 grams of fresh banana contains 32 milligrams of magnesium.

Seeds pack the highest magnesium concentrations — pumpkin seeds contain 503 milligrams per 100 grams and sunflower seeds 312 milligrams. Because seeds are so light, however, you need to eat a large volume to get a meaningful amount.

Nuts are a more practical source. Almonds stand out: they contain 322 milligrams per 100 grams, roughly 10 times the magnesium in a banana. A single handful of almonds — about 30 grams, delivering 96 milligrams — provides twice the magnesium of an entire banana (about 100 grams, or 32 milligrams), in a smaller serving.

Magnesium supports the brain, bones and heart, facilitating more than 300 enzymatic reactions, making adequate daily intake essential. A paper by researchers from Gyeongsang National University and Kyung Hee University, published in the international journal Nutrients in 2025, found that magnesium deficiency can raise the risk of metabolic disorders and a range of other chronic diseases. Common deficiency symptoms include eyelid twitching, muscle cramps, anxiety, insomnia, fatigue, heart palpitations, constipation and nausea.

Magnesium deficiency can make nights particularly difficult. It can trigger leg cramps during sleep and, because excessive stimulation reaches the brain unchecked, lead to insomnia. When levels are low, overstimulating signals flood the brain and make falling asleep harder. Magnesium acts as a kind of "gatekeeper," blocking the brain's NMDA receptor channels to regulate the flow of excessive excitatory signals.

Ji Eun-sil, an adviser at CellMed, a pharmacy-exclusive nutrition consulting brand and a pharmacist at Hyundai Pharmacy in Dangjin, said magnesium is "an essential mineral for muscle function and nervous system stability," adding that "nighttime muscle cramps and sleep disturbances are hallmark symptoms of magnesium deficiency."

Stress is one of the main drivers of magnesium depletion in the body. People under chronic stress are especially prone to losing magnesium. The two feed each other in a vicious cycle.

Ji said "the amount of magnesium excreted in urine increases under stress," and that "when magnesium becomes depleted, it amplifies the stress response in turn, making the body even more vulnerable to stress."

Eating refined carbohydrates while under stress makes things worse. Foods such as white rice, white bread and sugar contain almost no magnesium to begin with, and they spike blood sugar sharply, forcing the body to draw on even more magnesium to handle glucose metabolism and insulin signaling.

For those looking to top up their magnesium with supplements, taking small doses spread throughout the day is more effective than swallowing a large amount all at once. Ji explained that "because the body's homeostatic mechanisms (the processes that keep internal conditions stable) are always at work, magnesium absorption can increase up to fourfold when levels are low — but when the body already has enough, absorption actually drops."

The Ministry of Food and Drug Safety recommends a daily magnesium intake of 350 milligrams for adult men and 280 milligrams for adult women.