At night, it's harder for me to open my eyes. I wear contacts. Should I stop wearing them?

Maybe. Check for dry eyes. There are many types of lens materials and some are better suited to dry eyes. We often test tear film and treat dry eyes especially for our contact lens and lasik patients. Before you consider stopping lens wear, get checked out.
Maybe. If you are finding your contacts more difficult to tolerate, you may have a poor fit or an irritation related to the solution you are using. If your vision is unaffected and your eyes otherwise feel fine, you might start by trying a hydrogen peroxide solution like ciba clear care (it works differently - read the directions carefully). When in doubt, though, be sure to see your eyecare provider.