Using breathing to calm yourself before bed, or throughout the day to keep on top of anxiety can be incredibly useful:
I find both of these breathing pacing videos particularly useful, but make sure you have the sound turned on so that you can get used to doing it without watching so that you can fall asleep.
Headspace is also a brilliant app to begin meditating and calming yourself at night, which is very accessible. Meditation and mindfulness are vital to manage anaxiery and stress. Here is an interview regarding Headspace by Russell Brand: