Placing your iPhone on a solid surface such as the floor or a table while recording sleep causes MotionX to become highly sensitive to very small movements. This level of sensitivity is required for users sleeping on a very firm or motion-absorbing mattress (such as Tempur-Pedic).
However, with the iPhone on the floor or table, noise from the accelerometer sensor can be registered as sleep cycles resulting in a random sleep graph and random sleep statistics.
Ensure that you place your iPhone according to the instructions, either in bed or in an armband, so that MotionX can accurately monitor your sleep and wake you up at the optimal time. Please watch the in-app quickstart video to see how to position the iPhone optimally for best results.