Wake up feeling great

Each night your brain moves through several sleep cycles. At start of each cycle you enter light sleep, then move in to deep sleep, then dream and finally move back in to light sleep. These cycles take about 90 minutes each and you feel more refreshed if you wake up at the end of the cycle. Because you are then closest to your normal waking state

To increase the chances of this decide when you want to wake up, then count back in 90 minute blocks until you find the time when you want to fall to sleep. 

So let's imagine you want to wake up at 8 a.m., jumping back in 90 minute blocks will look like this. So you should aim to sleep around either at 11'o clock or half past 12 at night. 

Simply follow the 90 minute cycle and wake up feeling great.