How can I stop spiders from entering my room/house?

Okay, so, I'm a 15 year old girl and I don't cope well in spidery situations. I think I actually have a phobia rather than just being a bit scared of them, as in, if there is a spider in my room at night, I can't just squish it with a shoe or throw it out of the window, I will get out and sleep on the sofa and in the morning will have to have one of my parents check the whole room to see it's not there and clean my duvets/pillows etc, I really cant stand them, I'll shriek every time I see one and I'll lose sleep being paranoid that it will crawl on my face or something in my sleep and as it's getting warmer I have had my first encounter with a spider this year and I would love to know if there is any way of stopping them from wanting to come in. Thanks