Sulawesi shrimps' color fading off

[catohcat]

I'm keeping cardinal shrimps in my tank. I notice that when the light is off for a few hours, their color fade off. Has anyone experience this before? Is it a normal sign or bad sign ?

My tank parameter is:
PH: 8.0
GH: 12
KH:4
NO2: 0
NH3: 0

[sithspawn]

I think It's normal, Even normal fishes fade in colour after lights off at night. My sulawesi do that also anyway.