hello Sno76712,
it doesn't necessarily wake up because it's morning. it wakes up when it has had enough sleep, if you were to go to bed at 3 pm it would most likely wake its self up when it feels it has been well rested. so it all really depends on what time you go to bed and your sleeping habits, also it can also have to do with the alarm you have. it you are set to wake up at 6 am every morning your body will naturally start to wake up around that time, same as it would happen as your going to bed!
hope that makes sense :D