For all those who have an iPhone and know anything about sleep cycles, this post could help you feel more rested when you awake, which would carry with it other obvious benefits in the productiveness of your day.  You must, however, have a jailbroken iPhone, which I highly recommend anyway.  So, if you're jailbroken, then you'll find an app in Cydia called EasyWakeup.  If you've ever heard of the Sleep Tracker watch, it is supposed to work in the same way (except it doesn't cost you $150). Here's a clip from the developer's website explaining what it's designed to do in more detail:

EasyWakeup is a much better alternative to a traditional alarm clock. How often do you wake up each morning feeling tired? How often do you have to drag yourself out of a deep sleep to the sound of your annoying alarm clock? How often do you actually wake up feeling fully awake, alert and ready for your day? The reason you would wake up feeling tired is that there are several stages of sleep. The way you feel when you wake up each morning is completely dependent on which phase of sleep you wake up during. If you are in a heavy phase of sleep, then you wake up feeling sleepy and unrested. If you wake up in a lighter phase of sleep then you are alert and ready to begin your day. Our new clever alarm clock "Easy Wakeup" awakes you during one of your light phases of sleep using a scientific process. In order for this to work, the sleeper must attatch a part of the iPhone to their hand at night. Thanks to a special sensor on the phone, the program Easy Wakeup will wake you during one of your lightest phases of sleep. You will simply set a guide time in which your alarm must wake you, and the alarm will wake you up at the opportune time in your given time period.

I plan to write a review of the app once I have tested it a few times to see if it works.  You can get free activation keys from this offer: http://easywakeup.net/en/content/special-offer