Magnesium helps with sleep

This small clinical trial found that elderly people with low magnesium levels who took magnesium supplements for 8 weeks fell asleep faster, slept more efficiently, and had better scores on a standard insomnia questionnaire compared to those taking a placebo. However, the study tested so many different outcomes at once — without adjusting for that — that some of the positive results may be statistical flukes rather than real effects.

• The study only included elderly and overweight people who were already low in magnesium, so results may not apply to the general population
• 10 outcomes were tested simultaneously with no statistical correction; several key sleep findings don't hold up under standard correction rules
• People in the magnesium group also became more physically active during the trial, which independently improves sleep and wasn't accounted for
• The actual magnesium level in the blood barely changed, making it hard to confirm magnesium was truly the cause of the improvement
• Total sleep time — the most straightforward sleep measure — showed no significant benefit

This trial found that a specific patented form of magnesium (Magnesium-L-threonate) improved several secondary sleep measurements compared to placebo, but the main sleep test the study was designed to measure showed no significant difference between groups. Three of the six authors are paid employees or consultants of the company that funded the study and holds patents on the product — a conflict of interest hidden from the original publication and only revealed in a later correction notice.

• The primary outcome failed: both magnesium and placebo groups improved equally on the Insomnia Severity Index (p = 0.39)
• The study tested 50+ outcome variables but only corrected for comparisons within each measure, not across the whole set — most "significant" secondary results (p = 0.02–0.05) would not survive proper correction and likely reflect chance findings
• An unusually strong placebo effect makes it hard to attribute any benefit specifically to magnesium
• Participants were older on average in the magnesium group (~47 vs. ~44), an unadjusted confounder for sleep quality
• This study only tested a proprietary patented form of magnesium — results cannot be assumed to apply to common magnesium supplements