Yawning During Salah and Quran Time

Hey everyone, I've got this weird thing happening. Whenever I'm not praying or reading Quran, I feel totally normal. But as soon as I start my salah and get into reciting Surah Al-Fatiha, I just can't stop yawning. It's like the moment I finish praying, it goes away and I'm back to normal. Same thing happens with Quran recitation-I'm fine until I say 'Bismillah,' then the yawning kicks in. Any idea what's going on? Jazak Allah Khair for any advice.