Now, there will no doubt be a small group of you going 'Sleep Cycle? Seriously? That thing's been around forever!' And you're probably right. But I'VE only just discovered it, and honestly, I think it's amazing. Here's the gist, in a nutshell (and yes, I'm quoting directly from the website):
Have you ever woken up feeling completely wrecked when the alarm clock goes off, despite the fact that you have slept “enough” hours? When this happens you have probably been awakened during a deep sleep phase, and your whole day can turn into one long zombie marathon. Other days you spring out of bed with a smile on your face, feeling completely rested even though you shouldn’t. As the alarm clock goes off, chance seems to play a big role in how your day will become. But does it really have to be that way? This is where the Sleep Cycle alarm clock application comes into play.
During the night you go from light sleep to deep sleep, occasionally entering into a dream state which is called REM-sleep. These are things that your normal alarm clock does not care about, and will go off at the set time regardless of whether you are in a light sleep phase or in the deepest sleep. However, since you move differently in bed during the different phases, the Sleep Cycle alarm clock is able to use the accelerometer in your iPhone to monitor your movement and determine which sleep phase you are in. Sleep Cycle then uses a 30 minute alarm window that ends at your set alarm time and wakes you in your lightest sleep phase.
I actually heard about this App a while ago. You put your iPhone on the corner of your bed as you sleep, and it's sensor's pick up when you move and monitor how much you move to know how deeply you're awake or asleep. They then plot out a graph of your deep-light sleep cycle, and then wakes you up at the best part of the 30minute window you give it the night before so that you wake up feeling awesome! But it all sounded a little too fantastical and far-fetched, so I ignored it. But after (on the weekend) I heard my brother Ben talking about it and swearing by it, I decided to give it a go. I downloaded it for 99c from the AppStore, and have now used it for 3 nights in a row.
And here's what's absolutely amazing to me - this thing actually works! Like, seriously works! I never get more than 6 hours sleep during the week, and often need to get up very early (3 or 4am). And I have SUCH a hard time waking up and dragging myself through the next few hours until I've finally shaken it off and woken up properly. But the last 3 mornings in a row, when that little alarms has beeped, I've been WIDE AWAKE! Instantly. Awake. It's wonderful. Wonderful, wonderful, wonderful :)
SO. If you have an iPhone, you really need to give this a try. It's like a whole new world, where people can be people, and not zombies.