Current guidelines recommend that adults maintain optimal health and daytime performance by achieving a minimum of 7 hours of total sleep per night with a sleep efficiency of at least 85%.
Sleep Disorders – Global Status
Notably, a comprehensive global survey encompassing participants aged 15–65 highlights a significant prevalence of sleep disorders.
In the United States, 56% of respondents reported experiencing sleep disturbances, with 55–69% of those affected struggling with sleep initiation, 63–78% facing sleep maintenance issues, and 31–52% reporting poor overall sleep quality.
Similar trends were observed in Western Europe (31%) and Japan (23%), indicating that sleep disorders represent a widespread public health concern across different regions. Impairments in sleep quantity and quality can manifest as symptoms of sleep disorders, such as daytime somnolence, excessive daytime sleepiness, and nocturnal snoring.
Magnesium exerts a critical role in the physiological regulation of sleep-modulating substances
Magnesium (Mg), the second most abundant mineral in the human body, participates in over 300 biochemical reactions. Serving as an essential cofactor for numerous enzymatic reactions, it plays a pivotal role in maintaining cellular functions and physiological homeostasis.
Magnesium is pivotal to a wide array of biological processes, including oxidative phosphorylation, energy generation, glycolysis, and the biosynthesis of proteins and nucleic acids.
Magnesium ions also participate in muscle contraction, control neuronal excitability, and influence neurotransmitter cycling by regulating the transmembrane transport of other ions. This role is particularly crucial in the regulation of sleep.4
Magnesium in Melatonin and Serotonin Production
Several studies have demonstrated that magnesium deficiency in rats results in a reduction in plasma melatonin concentrations.
Magnesium is closely related to the production of melatonin. As a well-investigated and widely utilized sleep-promoting hormone, melatonin is a key regulator of the sleep-wake cycle and exhibits potent antioxidant properties.
An increase in oxidative stress may account for, at least in part, the poor sleep quality. Melatonin can enhance the activity of superoxide dismutase, thereby preventing oxidative stress-induced damage to cell membranes. When combined with omega-3 fatty acids, melatonin exerts an antioxidant effect by significantly enhancing superoxide dismutase activity in the human body.
Furthermore, endogenous melatonin has been shown to attenuate the excitatory neurotransmitter effects of L-glutamate by inhibiting specific NMDA receptor binding sites, thus promoting sleep.
Magnesium can also enhance the activity of serotonin N-acetyltransferase—an enzyme critical for melatonin synthesis.
Physiologically, magnesium interacts with the synthesis of serotonin and melatonin. Serotonin is an intermediate product in the production of melatonin, and melatonin is a metabolite of serotonin. The production of melatonin requires serotonin, and a deficiency or excess of serotonin can exert an impact on sleep duration and quality.
Magnesium also helps monoamine substances (such as serotonin) bind to their respective sites. The commonly discussed mechanism for increasing sleep duration is the pathway that promotes serotonin synthesis. Serotonin regulates most brain functions—including the sleep cycle—either directly or indirectly. Typically, serotonergic neurons collectively innervate numerous brain regions involved in sleep-wake behavior, functioning to promote consciousness and inhibit sleep.
5-hydroxytryptophan is generated from tryptophan through the catalysis of tryptophan hydroxylase and then converted into serotonin by the catalysis of 5-hydroxytryptophan decarboxylase. Tryptophan is a precursor to the neurotransmitter serotonin and the neurosecretory hormone melatonin, both of which are associated with sleep and alertness. Tryptophan can also regulate sleep and the circadian rhythm by increasing melatonin levels.
Magnesium in Insomnia
Insomnia stands as the most prevalent sleep disorder.
According to the International Classification of Sleep Disorders, the diagnosis of insomnia includes difficulties in initiating sleep, maintaining sleep, and subsequent impairment of daytime functioning.
In a human study, it was observed that long-term sleep deprivation decreased intracellular magnesium content and reduced exercise tolerance, which could subsequently be corrected through oral magnesium supplementation.
Nielsen et al conducted a study investigating the role of magnesium supplementation in adult sleep disorders, and following 7 weeks of treatment with 320 mg/day of magnesium citrate, patients exhibited an overall improvement in their PSQI scores.
Abbasi et al aimed to examine the effects of magnesium on insomnia in elderly individuals, and he administered 500 mg/day of magnesium to 46 elderly participants experiencing primary insomnia over an 8-week period, with outcomes including increased sleep duration and efficiency, as well as reduced ISI scores and sleep onset latency.
Additionally, it improved objective indicators of insomnia, such as the concentrations of serum renin, melatonin, and serum cortisol.
Three randomized controlled trials involving 151 elderly participants across three countries compared the effects of oral magnesium with placebo.
A systematic review and meta-analysis highlighted that, compared to placebo, magnesium supplementation reduced sleep onset latency by 17.36 min (P=0.0006) and extended total sleep time by 16.06 min, supporting the use of oral magnesium supplements (up to three times a day, with each dose less than 1 g) for treating insomnia symptoms.
Rondanelli et al found that, compared to placebo capsules, administering a formulation containing melatonin, magnesium, and zinc to 43 elderly subjects with primary insomnia, one hour before bedtime over an 8-week period, enhanced sleep quality and increased the total sleep time as measured by wearable arm sensors.
More recently, preliminary research by Honiak et al also concluded that magnesium supplementation could serve as a valuable alternative therapy for patients with insomnia.
In the treatment of insomnia, as an adjuvant therapy, magnesium not only acts as a natural NMDA antagonist and GABA agonist but also has a relaxing effect. Magnesium deficiency can cause muscle cramps, leading to poor sleep. Moreover, magnesium can increase melatonin levels, aiding in the maintenance of a normal biological clock and the alleviation of insomnia symptoms.
Another study further indicated that magnesium may alleviate insomnia associated with restless legs syndrome. Additionally, the serotonergic system represents another pathway potentially modulated by magnesium.
Magnesium in Idiopathic Hypersomnia and Narcolepsy
Idiopathic hypersomnia and narcolepsy are rare chronic sleep disorders that can impair patients’ cognitive function, social functioning, and health-related quality of life.
Their primary characteristic is excessive daytime sleepiness, with many narcolepsy patients also experiencing cataplexy. In addition, narcolepsy is associated with nighttime sleep disturbances, hypnagogic and hypnopompic hallucinations, as well as sleep paralysis. For idiopathic hypersomnia, extended nighttime sleep and sleep inertia are commonly observed.
Tunc et al conducted a study on 938 elderly outpatient patients and found that hypomagnesemia in the elderly is associated with excessive daytime sleepiness.
Recent research has also revealed a positive correlation between the Magnesium Deficiency Score and excessive sleep, especially among non-depressed elderly individuals.
Magnesium in Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) is defined by recurrent partial or complete collapse of the upper airway during sleep. Disruptions in respiratory airflow occur when the tongue and surrounding soft tissue structures prolapse into the pharynx due to gravitational forces and muscle relaxation, leading to a physical obstruction of the airway. These episodes lead to a complete or partial reduction in airflow and recurrent arousals.
The analysis by Zahraa et al also suggests that the severity of OSA affects serum Mg levels; the higher the AHI, the lower the serum Mg.
A recent study has also found a significant positive correlation between the Magnesium Deficiency Score and sleep apnea.
However, it remains unclear whether a decrease in serum Mg levels is one of the risk factors for OSA, or whether OSA directly leads to a decrease in serum Mg levels. Magnesium deficiency have the potential to inflict damage upon respiratory tract tissues, thereby heightening the susceptibility to airway collapse and potentially contributing to an increased incidence of sleep apnea.
Moreover, magnesium plays an integral role in hundreds of enzymatic reactions within biological systems, affecting important physiological activities such as nerve conduction and muscle contraction. Magnesium deficiency may impact the normal function of the respiratory muscles by affecting the conduction function of the nervous system, or it may directly act on muscle relaxation, leading to respiratory muscle dysfunction, especially in the respiratory muscles surrounding the pharynx, thereby elevating the incidence rate of sleep apnea.
Magnesium in RESTLESS LEG SYNDROME
Restless legs syndrome is a sensorimotor disorder characterized by abnormal sensations in the legs. Patients frequently experience a pronounced urge to move the affected limbs. These abnormal sensations are either partially or entirely expressed in the form of voluntary movements, such as walking.
These symptoms typically exhibit exacerbation during sleep and commonly precipitate sleep disturbances. This disease is categorized into two types: idiopathic and secondary. Pregnancy, uremia, iron deficiency, diabetes, and neuropathy are recognized as risk factors for the secondary variant of the disease. Nevertheless, the underlying pathophysiological mechanism of this disease remains incompletely.
A study has shown that patients with RLS/WED have lower magnesium levels compared to healthy control groups.
Several research investigations have similarly indicated that both oral and intravenous magnesium supplementation can be advantageous for these patients.
Sinniah et al reported that a patient with RLS/WED made a full recovery after receiving an intravenous injection of magnesium sulfate.
Additionally, another study suggests that oral magnesium supplementation may alleviate symptoms in individuals with moderate RLS.
For patients with mild to moderate RLS or insomnia associated with periodic limb movements during sleep, magnesium could serve as a viable alternative therapeutic option.
In the study of pregnant women, Yıldırım found that the concentrations of zinc and magnesium in pregnant women afflicted with this disease were significantly lower compared to those observed in other women. Furthermore, the study also established a correlation between these levels and the severity of the syndrome symptoms.
Specifically, there was an inverse relationship such that patients with lower serum magnesium and zinc levels presented with more severe symptoms. This suggests that magnesium may be regarded as a suitable alternative treatment for patients with RLS/WED.
More recently, the study by Honiak et al also reached the same conclusion, indicating that magnesium supplementation has the potential to serve as a beneficial alternative therapeutic approach for patients diagnosed with RLS.
Conclusion
Magnesium is intrinsically involved in sleep disorders through various mechanisms. An increasing body of evidence suggests a bidirectional relationship between magnesium deficiency and sleep disorders.
In specific sleep disorders, magnesium deficiency can contribute via two or more mechanisms, which may exhibit a synergistic effect. Magnesium deficiency may elevate neural excitability, increase muscle tension or exacerbate oxidative stress responses, thereby impairing the synthesis of sleep-inducing hormones, altering normal circadian rhythms and sleep architecture.
Conversely, sleep disorders can disrupt dietary magnesium intake and its absorption in the gastrointestinal tract, thereby contributing to magnesium deficiency in the body.
Magnesium supplementation can be integrated with traditional pharmacological and non-pharmacological interventions to implement comprehensive management strategies, offering new entry points for the diagnosis and treatment of these diseases.
