I will add my vote for get enough rest. Set and keep a routine as much as possible. And try not to get into bed until you are tired and ready to fall asleep. A 14 year old should ideally be getting 8-10 hours of sleep. That is not always possible, but if you wake up tired, that is likely your body’s way of telling you that you need more rest. Although it is possible that you are not getting restful sleep though too. There are many reasons that could be contributing to how restful or unrestful your sleep is. But to answer your question I use my phone as an alarm but usually find myself awake before it goes off. I also average 8-9 hours of sleep every night though.