Bed movements

During this project I tried to connect the movements sensors from an Angelcare Baby Monitor to the Arduino. I've tried to find out how the circuit works, but didn't end up with good results. The best I've got, looks like this:

Actually I've monitored my daughters bed. I've installed the sensor after 23 o'clock. Between 1 an 2 o'clock she was awake for about 30 minutes at least. We've got up in the morning around 8 o'clock.

After connecting the pressure panels to a new circuit, I've obtained the following diagrams:

Regarding the second graph, I want to say, that I went to bed around 22:50. I probably put my arm or a part of my pillow onto the sidebed of my daughter. Half past midnight, she switched from her room into her sidebed. We got up in the morning somewhat after 6 o'clock.

After changing and optimizing the data logging algorithm, I've got a much nice diagram:

This time, I went to bed around 22:30 and my daughter changed into her parents' room around 5 o'clock. The peak at 3 o'clock is due to the fact that, while asleep, I moved to close to the sensor pad. Finally, we got up in the morning at about 7 o'clock.