Although cats don't have to deal with rush hour traffic, exams, paying bills or missing deadlines, which causes stress in we humans, they also get stressed with their own problems in life.
A new member in family can make a cat stressed.
That member can be another cat, a new dog or simply a new person.
Cats are animals of habit.
So, sudden changes in their schedules can easily make them stressed.
So when you are doing changes in your house, do them smoothly as possible, giving your cat a little time to adjust to the new surrounding.
Cats treat your furniture as their own.
They mark them, so they can identify them with the scent.
Sometimes they scratch them to visually make item their own.
So sometimes, new furniture can make them stressed.
Now think about rearranging your furniture.
You can't let your pet know that you are rearranging the place, when your cat arrives; he would be shocked as he just can't recognize the things with smell or anything.
The places he knew very well have suddenly become unknown.
It will easily put him in tension.
So, when you are rearranging the house, always leave a little space for your cat which contains his toys and most familiar things, when he get use to new arrangements you can slowly change that space too(if you wish to).
Moving to a new house will also put him in stress because he doesn't know the reason to be in a new house.
You better keep and eye on him as sometimes otherwise he will try to go to old house and get lost in unknown land.
Fear can also make a cat stressed.
A mean dog in household or fireworks in holidays are few things that cat may get afraid of.
Whatever the reason your cat get stressed you can lower it simply by showing much love and sympathy to him.
Time he spend with you is the most valuable time he got, so play with him, give praise and kind words, spend little more time with him and enjoy the moment.