Could this be it?

Go to sleep my baby,
Close your pretty eyes.
Angel's up above you,
Watching my sweetie from the sky.
Great big moon is shining,
Stars begin to peep.
Time for sleepyheads like you
To go to sleep.

close variant also found...

Go to sleep, my baby.
Close your pretty eyes.
Angels watching o'er you,
peeping at you, darling,from the skies.
Great big moon is shining, high up in the sky.
Time to go to sleep, my pretty one.
Go to sleep