DS is almost 18... He goes to bed at 4 am! He has to be up for 6:50. He always has a nap when he gets home (for around 2 hours). He spends the night watching YouTube, Netflix, TV shows, etc. it's a nightmare! However, he's almost an adult, I can't always make choices for him. I wouldn't care, but his Sixth Form grades are really slipping. He started off so well, but failed last year, so is retaking it this year, he is absolutely capable, but barely writes down any of his work, we were called in for a meeting with his subject teachers and they said that if he doesn't start concentrating in lessons (tends to be yawning into the distance) he will no longer be able to stay at their Sixth Form. How do I fix this? I really don't want him to ruin his life from some sill decision to never go to bed!