[2muchcoffeeman]

I have been using Sleep Cycle too. Most the most part, yes, it does wake me up less cranky. You still need to allow for enough sleep though. If I only get ~6 hours of sleep. It wakes me up at an appropriate time - I feel better - but I am still tired - and thus crankier than usual.

[est]

The reviews on iTunes store says it's faking data and graph

http://itunes.apple.com/app/sleep-cycle-alarm-clock/id320606...

[underwater]

The creators countered by saying those reviewers were testing on uncalibrated phones. The app normalizes the movements so even if it detects only very small movements it will still render a graph with full range of movement.

I don't know if this is true but I saw in their changelog http://mdlabs.se/sleepcycle/changelog-v3.0.html that they "removed "dreaming" from graph legend we've done a lot of research around this with help from sleep scientists and determined that Sleep Cycle cannot reliably detect when you are in REM sleep".

That makes me think they're legit. Their test function is also pretty convincing. It detects large and small movements quite accurately.

[tudorachim]

If they can't detect when you're not in REM sleep and wake you up at that point, what's the point of the device?

[nater]

As I understand it, grogginess is associated with waking from deep sleep (no movement), not REM sleep.

[nater]

I was somewhat skeptical after reading some of the reviews, but after using the app for a couple of days I was satisfied that they're not faking data. I tend to wake up easily and have been able to match occasions when I wake up to the graphs.

I've been using the app for a couple of months and I feel that I am groggy less often when I wake up (though this could be expectation bias). It seems to work much better when I am sleeping alone I or my partner are traveling, though maybe this just means I need to buy a bigger bed.