Ok this is weird but honestly the sound of a ハート, 心 beating helps me sleep because it's soo calming. It helps me sleep better and like when hear someone's ハート, 心 beating it makes me feel all weak and just sleepy but in a 安全, 安全です feeling way. Like im secured forever in their arms. So yea heartbeats help me sleep :) I like to lay on a man's chest and just hear the beating in my ear and I fall asleep and it's like their ハート, 心 is gonna pop out of their chest または something cuz it's at a steady beat. And it's 音楽 to my ears.