Hi there,
That would be very draining for her to sleep like that.

First thing that came to my mind was if she had any illness or condition and whether she takes any particular medications or vitamins. Alcohol can affect sleep cycle too. Some people report vivid or lucid dreams more when they're taking certain things.

She sounds as if she's spending too much time in the stage of sleep where we all dream rather than other phases which allow her to rest.

Has she talked to her doctor about any of this?
There are many reasons why she might be having problems with her sleep cycle. Maybe get her to keep a bit of a sleep diary and then talk to her doctor about what's going on. A sleep study would be helpful if it continues. That would help the docs figure out why she's spending so much time in a particular phase of sleep.

http://www.helpguide.org/life/sleeping.htm
Getting the Sleep You Need:

http://www.helpguide.org/life/sleepi...es_sleep_cycle
What are the stages of sleep in the sleep cycle?

http://www.medicinenet.com/sleep/focus.htm
Sleep Health Center - What do you know about Sleep?

Let us know how she's doing.
take care,
Lara