Importance and benefits of magnesium

Magnesium (Mg) is one of five major minerals in the body that are essential for human health. It is an important cell-signalling molecule and a cofactor for hundreds of enzymes governing chemical reactions in the body.¹ Mg is involved in various processes in cells including energy production, DNA repair, vitamin D synthesis, and maintenance of healthy bone, normal cardiac rhythm, and electrolyte balance. 

More than half of the body’s Mg is concentrated in bone, around a quarter in muscle, and the remainder through other soft tissues and organs such as the brain, liver, and kidneys.²

Common symptoms of low Mg levels are 

• Muscle twitching and cramping
• Fatigue
• Mental confusion
• Nausea and loss of appetite
• Irregular heartbeat (cardiac arrhythmia)
• Chest pain or tightness

Mg deficiency can lead to serious health problems. Long-term deficiency can increase your risk of

• Kidney stones
• High blood pressure
• Heart disease
• Type 2 diabetes
• Osteoporosis
• Seizures

Other conditions that may be linked to low Magnesium levels are migraines, asthma, depression, anxiety, age-related cognitive decline and memory loss.

Sources of magnesium intake

Mg is abundant in dark green leafy vegetables and other fibrous plant foods such as legumes, nuts, seeds, and whole grains. 

The recommended daily intake (RDI) for adults assigned male at birth (AMAB) is 300 mg and for adults assigned female at birth (AFAB) 270 mg. However, despite its relative abundance in a variety of plant foods, 1 in 10 UK adults are not eating enough Mg to prevent deficiency.³

Some food products such as breakfast cereals are ‘fortified’ with Mg and other vitamins and minerals which are lost during processing and then added back. Products with Mg added may bear health claims relating to effects on teeth and bone health, electrolyte balance, and muscle and nerve function, under European Food Safety Authority rules.

Mg is available in supplements in pill and powder form, as bathing salts, topical skin preparations, and oral sprays. It is also used in over-the-counter medicines such as antacids and laxatives. 

Magnesium for sleep

Mg is purported to be a natural sleep aid. It is a common ingredient in supplements designed to support a good night’s rest, usually in combination with other ingredients including melatonin and vitamins B6 and B12.

Large dietary surveys have consistently found that populations with the highest intakes of Mg (along with other nutrients including calcium, vitamin D, and vitamin B6,) tend to report better sleep quality and duration compared to those with the lowest intakes.⁴ It remains unclear to what extent Mg in particular enhances sleep and or whether this is simply a benefit of eating an overall healthy balanced diet. There have been very few randomised controlled studies - (considered the gold standard of scientific evidence) which have looked at the effects of supplemental Mg on objective measures of sleep quality.

How does it affect your sleep?

Mg may lead to better sleep by easing muscular tension and by helping to relax us. 

Mg is involved in the regulation of muscle contraction and tone and naturally, relieves muscle cramps and spasms. In fact, muscle cramps and twitching are often the first signs of low Mg.

Bathing with Epsom salts, also known as magnesium sulphate is a well-known prescription for the relief of aching, tense muscles. However, there is little evidence for the absorption of Mg through the skin; though there is certainly no harm in trying this! A hot bath, with or without Epsom salts can ease tight muscles and promote feelings of relaxation and well-being that can contribute towards more restful sleep.

Mg may also aid better quality sleep by supporting normal energy levels and physical activity. Strenuous activity such as exercise increases ‘sleep pressure’ - the biological drive towards sleep that gradually builds throughout the day. Unexplained feelings of fatigue can be a symptom of Mg deficiency and may lead to a reduction in a person’s usual physical activity, making them less tired at night. Low energy may also encourage excessive daytime napping and the use of stimulants, such as caffeine, both of which are likely to interfere with an individual’s sleep routine.

Magnesium and the central nervous system

Mg is critical for the normal functioning of the nervous system, which includes our brain, spinal cord, and nerves. It helps regulate the activity of receptors that receive electrical messages from the higher brain centres. Mg is involved in the activation of the parasympathetic nervous system, responsible for the ‘rest and digest mode’, and deactivation of the sympathetic nervous system, responsible for the ‘fight or flight response’. It does this by inhibiting receptors for excitatory neurotransmitters such as epinephrine (also called adrenaline) and norepinephrine, and by activating receptors for inhibitory neurotransmitters such as gamma-aminobutyric acid (GABA).⁵ The prescription sleep drug Ambien^Ⓡ, induces drowsiness and sleep by acting on GABA receptors in the brain. 

As well as calming the mind and body, GABA activity helps to stimulate the pineal gland to produce melatonin, the hormone responsible for regulating the sleep/wake cycle. Additionally, by acting as a cofactor for melatonin production in the gut, Mg further helps sleep/wake cycle regulation .

Stress and antioxidant magnesium

Both physical and psychological or emotional stress increases free-radical oxidative damage, thereby increasing cellular demand for antioxidants. Oxidative damage causes inflammation throughout the body which has been linked to numerous chronic health conditions. These include heart disease, Type 2 diabetes, age-related cognitive impairment, anxiety and depression; all of which are also associated with Mg deficiency.

Mg is an important antioxidant. Individuals who are suffering from stress or depression tend to have low levels of magnesium because exposure to stress depletes the body’s stores of it. The relationship between stress and Mg may be bi-directional. Research suggests that not only does stress contribute to lower Mg levels, but low Mg may also, in turn, increase susceptibility to stress, and affective mood disorders such as anxiety and depression, thus forming a vicious circle.⁶

Stress, mood disorders, and sleep disturbances are frequent bed-fellows; racing thoughts, rumination, or the inability to fully relax can make it harder to drift off to sleep. Studies have shown a modest beneficial effect of Mg supplementation on psychological stress in people suffering from depression, anxiety disorders, premenstrual syndrome (PMS) and chronic pain conditions,^7,8 but whether this calming effect translates into improvements in sleep quality has not been independently studied.

Magnesium and Insomnia

Low Mg levels have been linked to insomnia, a sleep disorder characterised by persistent night-time wakefulness and difficulties in falling or staying asleep. It is the most common sleep disorder, affecting roughly one-third of all adults and up to half of adults over 55. Insomnia is also common in people with anxiety and depression.

The elderly are more likely to experience insomnia than the young. This may be partly due to age-related changes in the circadian rhythm resulting in increased sleep drive during the day and poor sleep routines. Seniors are also more prone to nutrient deficiencies due to poor diets and are more likely to be taking medications that can affect Mg absorption or excretion, thereby contributing to chronic Mg deficiency which may in turn lead to insomnia.⁹ 

Despite the observed association between low Mg and insomnia, randomised clinical trials conducted in older adults with insomnia have not been able to conclusively establish the effectiveness of taking oral Mg supplements.¹⁰  Nevertheless, studies that have looked at rates of insomnia and Mg intake among elderly populations have found that people with the highest Mg intakes tend to experience better sleep quality and lower rates of daytime drowsiness. 

Which form of magnesium is best for sleep?

There are many different forms of Mg supplements. Mg is well known for its laxative effect and certain forms of Mg used in supplements can cause gastrointestinal (GI) symptoms such as abdominal cramping, nausea, loose stools and diarrhoea. The NHS recommends that the maximum daily dose of Mg is 400 mg.

Forms of Mg that have shown promising results in randomised control trials include Mg-oxide and Mg citrate. In one study, healthy adults aged over 60 years who received 828 mg of Mg oxide for 8 weeks saw increases in sleep duration and a reduction in time taken to fall asleep.¹¹ Blood tests also showed an increase in serum melatonin and a reduction in serum cortisol - the primary hormone involved in the stress response that opposes the sleep-inducing actions of melatonin. 

The amount of Mg administered in the above study exceeds the limit generally accepted as safe and well tolerated. The study did not report any side effects such as GI symptoms, but Mg-oxide can have a laxative effect if taken in high doses and is a common ingredient in constipation remedies. However, Mg-oxide is poorly absorbed, which may account for the tolerance of the higher dose used in this study. 

In another study, seniors with sleep disturbances who received 320 mg of Mg-citrate daily for 7 weeks self-reported overall improvements in sleep quality.¹² When treating Magnesium deficiency, Mg-citrate is the form that is most easily absorbed by the body. However, it is also known for its laxative properties and so may not be well suited to those who suffer from GI complaints!

Other forms of Mg used in supplements are gentler on digestion. Mg-malate, Mg-threonate and Mg-glycinate are well tolerated, but there have been few studies that have looked at their impact on sleep.

The amino acid glycine is itself a natural sleep aid. It has a calming effect on central nervous system activity and has been found to: boost serotonin levels, help people to fall asleep faster, and increase the amount of time spent in deep sleep.¹³ It could be reasonably expected therefore that Mg and glycine combined (as Mg-glycinate, or bis-glycinate,) would prove a powerful soporific, however, more studies are needed.

Mg-threonate crosses the blood-brain barrier easily  raising Mg levels in the brain most effectively. It may also be protective against depression and age-related memory loss according to pre-clinical studies conducted in animals. Andrew Huberman, neuroscientist and tenured associate professor in the Department of Neurobiology, Psychiatry and Behavioural Sciences, Stanford University School of Medicine, recommends Mg-threonate or glycinate for improved cognition and aiding sleep, and says most people will benefit from 145 mg daily without any unwanted GI side effects.

So far research has only looked at the long-term effects of Mg supplementation and it is not known what the effect of a single dose of Mg has on sleep, if any.

Things to remember

Low levels of Mg may contribute to insomnia, stress and mental ill health, and there is some evidence to support its use for the treatment of insomnia, especially in older adults. Anecdotally, people report Mg has a calming effect, and there are several biological mechanisms that lend support to this claim. 

Most people can get enough Mg by eating a healthy balanced diet that includes a variety of vegetables, fruits, nuts, seeds and whole grains.

FAQs

How much magnesium should I take for sleep?

People who wish to take magnesium for sleep and who already eat a balanced diet are advised to start with 145 mg daily.

High doses of magnesium can cause GI upset and certain forms of magnesium used in some supplements may not be well tolerated in people who suffer from digestive complaints. The NHS-recommended upper limit for Mg in dietary supplements and over-the-counter medications is 400 mg daily.⁽⁴⁾ 

Is it OK to take magnesium every night?

Mg is generally safe to take every night, provided you do not exceed 400 mg daily.

Excessive Mg intake can lead to hypermagnesemia, a rare but serious condition where there is too much Mg in the blood. Hypermagnesemia can lead to mental confusion, slow breathing, low blood pressure, paralysis, and sudden cardiac arrest.¹⁴ Kidney disease can make toxic build-up of Mg more likely to occur, and people with kidney problems should not take Mg supplements without first consulting their doctor.

Which form of magnesium is best for sleep?

There is insufficient evidence to recommend any specific supplemental form of Mg for sleep. Some other ingredients that may be beneficial in combination with Mg²¹ are vitamins B6 and B12 and the amino acid tryptophan, which helps your body to produce melatonin and serotonin; amino acid L-theanine, which increases GABA and serotonin in the brain and the amino acid glycine.

Summary

Magnesium (Mg) is crucial for numerous functions, including energy production, DNA repair, and heart rhythm. Over half of it resides in bones, with significant portions in muscles and organs. Deficiency can manifest as muscle twitching, fatigue, and irregular heartbeat, leading to severe issues like heart disease and cognitive decline. While Mg-rich foods include leafy greens, nuts, and whole grains, many in the UK are deficient. Mg acts as a natural sleep enhancer, aiding muscle relaxation and influencing the nervous system. Chronic stress can further deplete Mg levels. Notably, low Mg may induce insomnia, especially in the elderly. There are various Mg supplements available, but for sleep benefits, starting with 145 mg daily without exceeding 400 mg is advised. A balanced diet is the best way to maintain Mg levels.