Some healing properties, perhaps? 

https://www.sciencealert.com/green-light-seems-to-relieve-pain-and-a-new-study-in-mice-shows-why

According to the article, not healing, just analgetic. That means it is not supposed to cure the cause of the pain, just supposed to make you less pain sensitive.

Well, that is the property of anything relieving stress levels. And soft green is known to do exactly that, reduce pain regardless of its origin.
Because what is pain? A signal, that something is not right and needs lower loading to heal. Stress means readiness to action, so it is important your mind is reminded of the limitations your body has. But when calm, there is no action anticipated, so no reason to reminding your mind about the problems.
It is the same reason, why clothing in hospitals is light green: It causes less stress so less fatigue for the staff working there for long hours.
Probably related to open grassy area, with no danger anywhere near and where any danger becomes observable way in advance, so one could relax.

At Carmel hospital, the clothing is white and azure.

Some healing properties, perhaps? 

https://www.sciencealert.com/green-light-seems-to-relieve-pain-and-a-new-study-in-mice-shows-why

Animal experimentation. Lovely, just the sort of thing to discuss on LG. Not 

Animal experimentation. Lovely, just the sort of thing to discuss on LG. Not 

Yeah, I'm with you on this one.