A recent study from the Nutrition Journal sought to determine if isoflavones from food would have a positive impact on sleep duration and quality. Researchers analyzed the diets and sleep patterns of more than 1,000 Japanese adults to assess daily isoflavone intake and sleep quality. Higher isoflavone intake, from 22mg to 166mg in a 2,000 calorie day, was positively associated with optimal sleep duration and quality in the Japanese population. Soyfoods are a common source of isoflavones, for example, firm tofu has about 19mg of isoflavones per half-cup serving, soymilk has 26mg per 1-cup serving, and 1 ounce of soy protein isolate has 27mg, according to the USDA database. These findings suggests that daily isoflavone intake from soyfoods may have a potentially beneficial effect on getting a good night?s sleep.