Supposedly if you wake up on your own at the end of one of your sleep cycles, you feel better. The snooze button is supposed to be bad for sleep as you don't get properly back to sleep and tend to wake up in the middle of your sleep cycle which makes you more sleepy. So it's better to wake up naturally a bit earlier or slightly later at the end of one of your sleep cycles than it is to pick an arbitrary time and use the alarm. I hardly ever use an alarm unless i really need to be up and then I usually just get up before it goes off so I don't go into zombie mode.