I have panic attacks when I lay down and try to sleep. What can I do to stop them?

Relax. Assuming medical problems have been ruled out there are lots of things to help reduce anxiety before sleep. One can't be relaxed and anxious, so reducing stimulants such as cigarettes and coffee, late eating, or stimulating activity before bed can help - relaxation exercises, deep breathing, soothing activities before bed are wise. A clinical psychologist can help with these if one has trouble.