Is she tired all the time?
I only ask as it may just be that she doesn’t need much sleep and, in which case,I wouldn’t worry about it.
Otherwise (and some of these are probably obvious!)
...has she tried white noise?
Or going to bed later and sleeping further into the morning.
My missus often uses lavender oil to help when she has problems sleeping
Try an eye mask.
Cut out blue light before bedtime.
Cut out caffeine and alcohol.
Take melatonin supplements.
.