It seems the Japanese studies were mainly focused on the sleep-friendly properties of white rice, as that’s the more popularly consumed type of rice in Japan.
White rice has a glycemic index (GI) of 72, which is considered high. The researchers of the 2014 study hypothesize that high-GI foods boost the presence of the amino acid tryptophan in the brain, which in turn converts into serotonin and the sleep hormone melatonin. According to nutritionist Anjali Mukerjee (via India.com), “[White rice] releases calming hormones like melatonin and serotonin that calls [sic] for relaxation and drowsiness.”
Brown rice has sleep-inducing benefits too. In addition to the sleep-promoting magnesium and vitamins B3 and B6, it contains GABA (gamma-aminobutyric acid), which relaxes your nervous system by slowing down brain activity. Brown rice is considered a low-GI food (GI 50). However, according to Dr. Chin Moi Chow from the University of Sydney, eating starchy sticky rice (higher-GI jasmine rice) put participants to sleep faster than when they consumed low-GI long-grain rice in a study she conducted (via The Sydney Morning Herald).
Now that you have a common carb to add to your list of foods you never knew could help your sleep, what does this mean for eating rice at night?