Does she have an idea for what is keeping her up, or does it seem purely physical? Has anything else changed?
I would try:
Things to release stress.
Make sure she is getting some movement and/or exercise.
Getting sunlight in the day.
Getting up at the same time every morning.
Make sure she has a list of things to do/a journal for worries, in particular if the pregnancy has brought on anything new in that arena, and write it all out before bed.
Don’t have any screen time later in the evening/night.
Don’t have anything caffeinated or chocolate after noon.
Drink calming tea before bed.