Yogis have been practicing Chandra Bhedana Pranayama, aka Moon Breathing, aka breathing through one nostril, for centuries. It’s believed to help slow down busy minds, relax the body, and promote a restful sleep.
To do it, get comfortable, and try to release any tension you might be holding in your face. Place the index and middle finger of your right hand on your third eye (that point between your eyebrows but a smidge higher), then block your right nostril with your thumb. Take a deep inhalation through your left nostril, hold the breath while you block your left nostril with your ring finger, remove your thumb from your right nostril, and exhale from the right. Then inhale from the right, block with your thumb, hold, unblock your left, exhale. Keep doing this for a few minutes, just focusing on your breath, and you’ll be chilled enough to sleep in no time.