Why do you yawn when you are tired?
Why do we yawn when we are sleepy?
Why do we yawn? Why do we yawn? Why do we yawn? What is the reason? Why do I yawn when others yawn? Why do we yawn when we're bored? Why do people yawn when someone yawns in front? What is the purpose of yawning? Why do I yawn when I get excited? What does it mean when a dog yawns and isn't tired? I yawn a lot at night, what could be the reason? Why do I almost always yawn after an orgasm? Which is the biological purpose of a yawn? Why do mammals yawn and stretch? Can someone yawn or sneeze while he is asleep? Why do people in a group starts yawning simultaneously if someone in group yawns? Why does my throat hurt when I yawn? Why does yawning make your singing/speaking voice so good? Why are yawns sometimes synchronized or sympathetic between two or more people? Why do we fall asleep? Why am I sleepy all the time? Why does yawning increase your heart rate so much? Why do you feel so sleepy? What does it mean when your dog yawns after you yawn? Why am I so sleepy lately? How can I be less sleepy? Why do we feel sleepy in morning? How can I overcome it? Why do we cry while sleeping? Why am I always sleepy and how can I avoid it? Why do I feel so sleepy so often? Why don't we sleep when we are awake? Why are you tired after you wake up from a nap?