From the Guidelines
The optimal timing for taking magnesium supplements is in the evening, about 1-2 hours before bedtime, as it can help prepare the body for sleep and alleviate constipation-related symptoms. This recommendation is based on the natural relaxing properties of magnesium and its ability to regulate neurotransmitters that calm the nervous system 1. When taking magnesium, it is essential to consider the dosage, with a standard dose of 200-400mg being commonly recommended, and to take it with a small snack or meal to improve absorption and reduce potential digestive discomfort.
Some key points to consider when taking magnesium supplements include:
- Consistency is more important than exact timing, especially when taking magnesium for specific health concerns like muscle cramps or constipation 1
- Splitting the magnesium dose, taking half in the morning and half in the evening, may be beneficial for those taking higher doses
- Magnesium works by regulating neurotransmitters that calm the nervous system and by helping muscles relax, which explains its effectiveness as an evening supplement
- If loose stools occur, consider switching to a more easily tolerated form like magnesium glycinate or reducing the dose
It is also crucial to note that magnesium supplements should be avoided in individuals with significant renal impairment, as hypermagnesemia is more likely to occur in these cases 1. The most recent and highest quality study on the topic, published in 2023, provides guidance on the use of magnesium oxide for chronic idiopathic constipation, but does not specifically address the optimal timing for taking magnesium supplements 1. However, based on the available evidence and general medical knowledge, taking magnesium in the evening appears to be the most beneficial approach.
From the FDA Drug Label
Directions ... As a Laxative ... dose may be taken once a day preferably at bedtime, in divided doses, or as directed by a doctor. The optimal timing for taking magnesium supplements as a laxative is preferably at bedtime or in divided doses, as directed by a doctor 2.
- The dose can be taken once a day,
- Preferably at bedtime,
- Or in divided doses.
From the Research
Optimal Timing for Taking Magnesium Supplements
There is no specific evidence in the provided studies that directly addresses the optimal timing for taking magnesium supplements.
General Information on Magnesium Supplementation
- Magnesium is essential for many physiological functions in the human body, including maintaining normal cellular physiology and metabolism, and regulating ion channels and energy generation 3, 4, 5.
- The optimal magnesium intake is not well established, but higher magnesium concentrations are associated with better survival in patients with chronic kidney disease 5.
- Magnesium supplementation has been shown to improve sleep quality and daytime functioning in adults with self-reported sleep problems 6.
- Dietary magnesium intake may have long-term benefits in reducing the likelihood of daytime falling asleep in women 7.
Considerations for Magnesium Supplementation
- Magnesium homeostasis involves dietary intake, absorption, uptake and release from bone, swifts between the intra- and extracellular compartment, and renal excretion 5.
- Renal excretion is mainly responsible for regulation of magnesium balance, and kidney disorders can potentially lead to both magnesium depletion and overload 3, 5.
- The reference ranges for magnesium are not necessarily optimal concentrations, and risks for insufficient magnesium intake exist in patients with chronic kidney disease 5.
Magnesium and Sleep
- Magnesium has been implicated to benefit sleep, although the clinical evidences varied based on the magnesium source used 6, 7.
- Magnesium L-threonate (MgT) is a promising intervention due to its brain bioavailability and effects on cognition, memory and mood 6.
- MgT supplementation has been shown to improve sleep quality, especially deep/REM sleep stages, and improve mood, energy, alertness, and daily activity and productivity 6.