/diy/ - Do It Yourself

I made this capacitive detector with a small piece of aluminium foil and it works great.
Basically two pins on the arduino are connected with a 1M resistor and from the resistor goes a 1 meter wire attached to an aluminum foil, which is glued on the inside of a closet door.
So when a human places a hand near the foil, he acts as a cap and leeches away some of the voltage, causing the second pin to receive the voltage at a small delay. This delay is measured by the arduino.
But the problem is, after i leave it running for a while, it starts throwing out higher values that normal (like 10x higher) even though there are no humans or anything else nearby and i have to manually restart the arduino.

https://playground.arduino.cc/Main/CapacitiveSensor?from=Main.CapSense

Any idea what is going on here? Is my apartment haunted? Is some asshole ghost jacking on top of the arduino generating electromagnetic fields which are triggering my shit?