7 Signs You Might Be Low on Magnesium (And What to Do About It)

1. Muscle Cramps and Spasms

Magnesium plays a critical role in muscle contraction and relaxation. It acts as a natural calcium channel blocker — when magnesium levels are adequate, muscles can relax properly after contracting. When levels are low, calcium can overstimulate muscle fibers, leading to cramps, twitches, and spasms.

Garrison et al. (2012) published a Cochrane review examining magnesium supplementation for muscle cramps and found evidence suggesting that magnesium may help reduce cramp frequency, particularly in populations prone to deficiency. If you experience frequent calf cramps, eye twitches, or muscle tension — especially at night — low magnesium may be a contributing factor.

2. Poor Sleep Quality

Magnesium is directly involved in the regulation of melatonin and GABA — two key players in the sleep-wake cycle. GABA (gamma-aminobutyric acid) is the brain's primary inhibitory neurotransmitter, responsible for calming neural activity and promoting the transition from wakefulness to sleep.

Abbasi et al. (2012) conducted a double-blind, placebo-controlled trial published in the Journal of Research in Medical Sciences and found that magnesium supplementation (500mg daily) significantly improved subjective sleep quality, sleep time, sleep efficiency, and serum melatonin levels in elderly subjects with insomnia. Participants also showed reduced cortisol levels — the stress hormone that can interfere with sleep onset.

If you find yourself lying awake despite feeling tired, or waking frequently during the night, your magnesium status may be worth investigating.

3. Anxiety and Restlessness

The relationship between magnesium and anxiety is well-documented in the scientific literature. Boyle et al. (2017) published a systematic review in Nutrients analyzing 18 studies and concluded that existing evidence suggests magnesium supplementation may have a beneficial effect on subjective anxiety in anxiety-prone individuals.

The mechanism is believed to involve magnesium's role in regulating the hypothalamic-pituitary-adrenal (HPA) axis — the body's central stress response system. When magnesium is insufficient, the HPA axis may become overactive, leading to elevated cortisol and a persistent feeling of being "wired but tired."

If you experience unexplained anxiety, nervousness, or an inability to relax — particularly in the evening — low magnesium may be part of the picture.

4. Brain Fog and Difficulty Concentrating

Magnesium is essential for synaptic plasticity — the brain's ability to form and strengthen neural connections, which underlies learning, memory, and cognitive clarity. Slutsky et al. (2010) published a groundbreaking study in Neuron showing that increasing brain magnesium levels enhanced both short-term and long-term memory in animal models, and that this effect was mediated through improved synaptic density and plasticity.

While human studies are still emerging, the mechanistic evidence is strong: magnesium modulates NMDA receptors, which are central to learning and memory formation. When magnesium levels are suboptimal, these receptors may become overexcited by glutamate, potentially leading to cognitive fatigue, difficulty concentrating, and the subjective experience of "brain fog."

5. Persistent Fatigue

Magnesium is required for the production of adenosine triphosphate (ATP) — the molecule that powers virtually every cellular process in the body. Without adequate magnesium, the enzyme ATP synthase cannot function efficiently, and cellular energy production may decline.

Desbrow et al. (2012) published research in the European Journal of Clinical Nutrition examining the relationship between magnesium status and exercise performance, finding that even marginal deficiency could reduce energy efficiency and increase the oxygen cost of physical activity. In practical terms, this means low magnesium may make everyday activities feel more physically taxing than they should.

If you feel chronically tired despite adequate sleep and nutrition, magnesium status is one of the variables worth examining with your healthcare provider.

6. Irregular Heartbeat

The heart is a muscle, and like all muscles, it depends on the precise balance of magnesium, calcium, and potassium to contract and relax rhythmically. Magnesium deficiency has been associated with cardiac arrhythmias — irregular heartbeat patterns that can range from benign palpitations to more serious conditions.

DiNicolantonio et al. (2018) published a comprehensive review in Open Heart arguing that subclinical magnesium deficiency is a principal driver of cardiovascular disease and that current recommended daily intake levels may be insufficient for optimal heart health. The researchers noted that magnesium's role in maintaining normal heart rhythm is so critical that intravenous magnesium is routinely used in emergency departments to treat certain types of arrhythmia.

Note: irregular heartbeat can have many causes. If you experience persistent palpitations or arrhythmia, consult a healthcare provider for proper evaluation.

7. Frequent Headaches

Multiple studies have found associations between low magnesium levels and headache frequency. Mauskop and Varughese (2012) published a review in the Journal of Neural Transmission examining the role of magnesium in headache pathophysiology and concluded that magnesium deficiency may be present in a significant portion of headache sufferers, and that supplementation may help reduce frequency in certain populations.

The proposed mechanism involves magnesium's role in regulating neurotransmitter release, blood vessel tone, and inflammatory signaling. The American Academy of Neurology and the American Headache Society have acknowledged magnesium as a potentially effective option, classifying it as "probably effective" based on available evidence.

Dietary Sources: Are They Enough?

Magnesium-rich foods include dark leafy greens (spinach, Swiss chard), pumpkin seeds, almonds, black beans, dark chocolate, and avocados. The Recommended Dietary Allowance (RDA) is 400–420mg for adult men and 310–320mg for adult women.

In theory, a well-designed whole-food diet can meet these needs. In practice, it rarely does. The 2015–2020 Dietary Guidelines for Americans identified magnesium as a "nutrient of public health concern" due to widespread underconsumption. Modern farming practices have reduced the mineral content of soil — and therefore of the crops grown in it. A study by Thomas (2007) in Nutrition and Health found that the magnesium content of commonly consumed foods declined by an average of 20–30% between 1940 and 2002.

This gap between dietary intake and physiological need is why many researchers and clinicians suggest that targeted supplementation may be beneficial — particularly for active individuals whose magnesium needs are elevated by exercise-induced losses through sweat and increased metabolic demand.

Why Glycinate Is the Form That Matters

Not all magnesium supplements are created equal. The form of magnesium determines both its bioavailability (how well it's absorbed) and its effects on the body.

Magnesium oxide — the most common and cheapest form — has a bioavailability of roughly 4%, meaning that the vast majority passes through the body unabsorbed (and often causes digestive upset). Magnesium citrate is better absorbed but is primarily known for its laxative effect. Magnesium glycinate — magnesium bound to the amino acid glycine — offers a distinct advantage.

Schuette et al. (1994) published research in the Journal of the American College of Nutrition demonstrating that chelated forms of magnesium (including glycinate) showed superior absorption compared to inorganic forms. The glycine component is itself bioactive: it serves as an inhibitory neurotransmitter, supports collagen synthesis, and has been independently shown to improve sleep quality.

Bannai et al. (2012) found in Frontiers in Neurology that glycine supplementation before bed lowered core body temperature and improved subjective sleep quality. In magnesium glycinate, you get both the mineral and the amino acid working together — making it the ideal form for evening supplementation.

Closing the Gap

If you recognize yourself in several of the signs above, you're not alone — and you're not imagining it. Subclinical magnesium deficiency is extremely common and often overlooked because standard blood tests (serum magnesium) only reflect about 1% of total body magnesium. You can have "normal" blood levels while your cells, muscles, and bones are depleted.

The first step is improving dietary intake through magnesium-rich whole foods. The second is targeted supplementation with a highly bioavailable form. CHRY includes 300mg of magnesium glycinate in every stick pack — a meaningful dose in the form that research suggests is best absorbed and most beneficial for evening use.

Your body runs on magnesium. Make sure it has enough.