I sometimes talk to myself, and try to befriend the fear.

I talk to the hypervigilant part, and tell it 'Thank You' for trying to keep me safe.
I let it know that I need to sleep now, and that it is ok for it to rest.

If the mental talk doesn't work, usually doing something physical helps. I dance around the house, run in place until I'm out of breath, clean the heck out of the bathroom -- whatever I feel like. Engaging the physical body is a great way to slow the mental processes down.