This special scent (odourless to people and other animals) that Feliway utilizes is a replication of the pheromone that cats leave naturally when they are feeling comfortable in their environment. 

Every time a cat rubs its nose against objects in the home, it leaves behind this pheromone to mark its territory. 

Even small changes in your home can upset your cat and prevent them from leaving this pheromone, which in turn makes them feel less secure, and increases their stress. 

Activities such as redecorating, moving the furniture, having guests, going to the cattery and moving home will remove these natural pheromones for your cat, causing it stress. 

Your cat may also be affected by any change in your home organisation and schedule: new family member such as a baby or a new partner, a new job making you more absent from the home, etc. Cats are very sensitive to a routine and stable environment. 

Stress can lead to unhappy behaviour such as less interaction with you, hiding away, general mischief or even scratching or spraying. 

Refill should last 4 weeks. 
It covers an area of 50-70m2 
Do not plug in behind a door, curtain or behind/underneath furniture. 
Replace the diffuser every 6 months.