Did you wake up today with a sudden fear caused by the realization danger? No? That's the definition of the word "alarm".
Your body can't tell the difference between serious threat and your clock. Otherwise you wouldn't wake up every morning. Understand: While you sleep the brain is not twirling its thumbs. It does essential work - and it takes a lot to interrupt it. If you have to, please don't do so while the brain is in the midst of a task. Learn about natural sleep cycles and set your alarm accordingly.
Let's say it takes 15 minutes to fall asleep, your first sleep cycle lasts 60 minutes and all following ones are 90 minutes long. A good time to wake up would then be 5h45min, 7h15min or 8h45min after you turned out the lights. This is just a guide value. Try it and see what works best for you. Since I first heard about this I abandoned the recommended eight hours. Instead I switch between 7h15min and 8h45min depending on how tired I feel.
I strongly recommend reading more on this topic although I'm going to share my knowledge with you here, of course. But not now. I'm tired. Good Night.