Its very simple and can be used with any God or Goddess your drawn to at night. You could change depending on the month or time of year, its up to you.
I like to keep the same God & Goddess when i say this
"As i lay my head down to sleep,
I prayer my soul for ___?___ to keep."
You could finish with blessed be, its up to you. I personally don't but I feel safe at night when i say this, out load or in my mind.
You could add a wake up verse if u wanted, I'm not sure if i have one lol i tend to sit up for a bit when i wake up and not move, so who knows whats running through my noggin haha
Can't sleep atm which is ironic, but hoping to doze once ive written this