Here is a simple method, which I've used for years, to wake up at the correct time without using an alarm.
Step 1: Do This!
Before going to bed do the following:
- Drink a glass of water.
- Tell to your inner mind that, you wanna wake up at this time and do a certain work(specify the work).
Note: For a first few tries, kindly set an alarm, which will ring half hour later from the time you wanted to wake up.