Need your help with my sleep bruxism🙏🥺

I am 18 and I have sleep bruxism. It is basically clenching and grinding your teeth in sleep,which means you do it unconsciously and have no control over it. It has literally ruined my life and I wake up everyday feeling so exhausted,with intense migraines and pain in jaw. But my dad does not believe me bcs for him,I am sleeping 9 hours everyday alomg with sleeping in afternoon. I want to record myself sleeping as a proof and also to know the cause. So pls tell me some jugaad or somtheing I can do with my phone. Or some cameras which can record for 7 hours straight.Low light vision and sound is not necessary. Also need to do it for only 1-3days,so want to go as cheap as possible.