Calcium supports sleep in two ways. First, it helps the body convert tryptophan into melatonin. Dairy products, which contain both tryptophan and calcium, are among the most sleep-promoting of all foods. A warm glass of milk at bedtime is a cliché for a reason.
Secondly, calcium — along with zinc, copper, and magnesium — supports the signaling process that governs the sleep–wake cycle. Functional nutritionist Jesse Haas, CNS, LN, calls these nutrients gatekeepers that “let information in and out of cells and move brain chemicals around.”
Whole-Food Sources: Good sources of calcium include kale, sardines with bones, tofu, yogurt, edamame, figs, almonds, and cottage cheese.
Supplements: Calcium-citrate supplements offer a potentially more bioavailable option for getting this nutrient; these often combine calcium with another sleep-supportive nutrient — magnesium. (For more on wise ways to supplement calcium, and how to best combine it with other nutrients, see “How to Optimize Your Calcium Intake“.)