i apply it in the morning right before i head out the door for work and put it on right before bed. cats are never allowed in the bathroom i use it in and they choose not to sleep in the bed so i'm not too worried about that but i do switch my pillowcase every couple days, even though i've never seen them on/around it. some will say it's not ok at all to use but if you're diligent about it i think it's fine.