BlueBelle, you say your GS doesn’t wake up even if he has gone to bed early, but you also say he burns the candle at both ends. If he has a pattern of not getting enough sleep then one longer sleep won’t necessarily make a difference, but a pattern of getting enough sleep might do. It sounds like the first thing to try is going to bed every day 9 hours before the time he wants to wake up. (Teenagers need more sleep than adults. Also, as a sleep cycle is about 45 minutes long, sleeping 8 1/4 or 9 hours avoids waking up in the middle of a sleep cycle, which is harder to do.)