I highly recommend this little app for .99cents, if you have an iPhone (3 or 4), an iPod touch, or an iPad (1 or 2). You load the app, set the alarm, and put it on the mattress next to you face down without turning your device off. It maps your sleep cycles all night. In the morning it generates a lovely little graph for you. It is one of the best selling apps in the world, and it is not hard to see why.
Not only that, but it is an alarm clock that will gently wake you when you are in your lightest sleep phase in the half hour time period you set for the alarm.
You can learn a a lot about your sleep habits, and perhaps how to improve them so that you wake feeling refreshed, and ready for the day.
I've only used it twice, and have included my graphs too, at the end of this article.
Quoted from Sleep Cycle's website: http://www.sleepcycle.com/
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.
"This isn't really something new. These so called bio-alarm clocks have been around for years and work very well, but they usually come with a hefty $200 price tag. I realized that the iPhone has all the components needed, and decided to make an alarm clock that works exactly the same, but sell it for a dollar or two instead."Maciek Drejak, the programmer behind the application, says.
Example 1: a typical sleep graph
|Example 2: more irregular sleep with a period|
of being awake or nearly awake at 6am
The second example has a bit more irregular sleep. The user did probably not sleep as well as in example 1. In this example the user's partner got up at 6am. This is clearly seen - the user was awake or nearly awake at around 6am when her or his partner got up.
My graphs from two recent nights.