Many of my feline friends have found their forever homes after a spell in a cat shelter. Otherwise they would have continued to live rough on the street.
So shelters are good - but they are also very stressful for some of us. Most of us cats settle in fairly well and start to feel at home once we have rubbed our scent on the shelter surroundings and got used to strange noises, strange people and strange smells.
Most but not all. Some of us cats are particularly prone to stress and for us stressy cats time in a shelter can be hell - unless we have somewhere to hide.
So we do the best we can to hide. We close our eyes and pretend to sleep. Most humans think we are sleeping.
But the most intelligent humans can see that we are not - our bodies are tense and uptight, not relaxed and spread out, our feet are under our shoulders and firmly on the ground ready to run away, our ears are pointing downwards from anxiety, and every now and again we open an eye.
Here is a video of a cat pretending to sleep. Show it to your human, so that they can spot the signs. If they work in shelter, a cat who copes by pretending to sleep needs a hiding box.