Adequate way to connect sensors far away from arduino
I would consider using some capacitors, clamping diodes, and output resistors very close to the arduino. 

The long wires will have capactive and inductive loads. Bumps to the wire will create noise spikes. 


The output resistors (input to the arduino) will limit the spike based on the current surge (should be low, 10k resistor should be fine). 
The capacitor will stabilize the voltage, select the capacitor value based on a low pass filter RC equation and the expected frequency of the light changing (f = 1/2*piRC). If it's just ambient light in a room go with 10uF or whatever is available, if its a strobing diode, calculate the filter value.
For the clamping diode, pick a fast response time diode that clamps at a little over 5V so the noise spikes, and ESD, from tapping the wire doesn't kill the input pin on your arduino. The P6KE6V8CA should do the trick.