Green Light during Dark Period

Technically it's possible for there to be a light that wouldn't disturb the dark cycle, but entering your space probably involves compromising the light-proofness anyway plus what would you see? Everything would look black or green, barely worth it.
 
Just stay out during the dark cycle.

 

I use a green led bulb in the ceiling between the tents as the only light in that area of the room (its partitioned off).  I also have a led work light and a head lamp.  People that have no experience should keep their lack of experience to themselves. 
 
The reason why we use a green light is that the plant does not absorb green light, it reflects it.  Plants have no idea that there is a green light on.  Anybody that has had to do work in the dark period must use these.  Being safe for your girls is never a bad idea, so get yourself some green bulbs and know that you are being safe.  
 
If you were to use any type of foliar treatments, they must be applied in the dark.  Seeing what you are doing while working in the dark, I would say is more than "barely worth it".

 

 
I've heard people using them but personally I wouldn't trust it. It may be predominantly green but can you be sure it's only green light coming through and whether the plant definitely won't see anything. I sometimes open up my tent for a few seconds or maybe a couple of minutes without having any problems. I wouldn't do it two days in a row, but I have yet to have any issues from this 
 
Edit..
plants do absorb a small amount of green light but it doesn't seem to trigger their perception of day/night. You would be putting a lot of faith in the manufacturer of that bulb. It's not something I would find worth the risk 

 

I am sorry, but you are wrong.  Green light IS reflected by plants.  Chlorophyll absorbs light in the red (long wavelength) and the blue (short wavelength) regions of the visible light spectrum. Green light is not absorbed but reflected, making the plant appear green.

 

 
Yes I went to school when I was 8 so I'm aware of that. But they do absorb a small amount of green light. It's commonly agreed upon that this is the case 

 

Dude, you are wrong.  Accept it.  Attempting to be disrespectful wont change that.  The entire scientific community believes that plants absorb red and blue light.  They reflect green and yellow and always have.  Go and check out a spectrum chart so you can educate yourself past the 8 year old you are acting like.
 
This is basic physics:  The color you see, is the color that is reflected. 

 

I would side with MP on this one.
   http://www.webexhibits.org/causesofcolor/7A.html
 
What i am not sure of is white light penetrating through a green colored lens. If the wavelengths of the red and blue still have an effect on the photocells of the plant is what I would have the slightest concern about.
 
The reduced intensity or lack thereof from a head lamp is where I would not worry though.

 

All of the green lights I use are green "plant safe" LEDs and are not colored lenses.  

 

The OP was considering a setting on his phone. I would not recommend it.

 

Nor would I.