This is not news to yogis, but it's great to see clinical research that enhances our understanding of the relationship between body, breath, and mind. Nasal respiration might be the single most important thing that I teach in my classes, and I teach it to everyone! Like my teacher Mira of Global Family Yoga says and I often repeat, your mouth is for talking and eating, but when it's comes to breathing it's just a backup system in case you have a cold.
Grownups often tell worked-up kids to take a breath. It's great advice, but be specific - breathe in and out through your nose!