Let's say you went to bed at 1 AM last night. To make matters worse, you've used iSleep to watch a movie till 2:30 AM. It's 6 AM and iSleep wakes you up. You know that you have to get up, but you just want 5 minutes to get less drowsy, but you're afraid and don't want to get asleep again.
iSleep can solve your problem ! When iSleep wakes you up, just Snooze :-) Only one keypress in needed : hit the space bar and iSleep will let you sleep for 5 minutes before firing up the music again.
Of course, if you're a sleepyhead and usually need 10 more minutes to sleep a little more instead of 5, you can just change that delay in the Preferences ("Alarm Clock" tab).