The option for a sleep aid in the form of melatonin in a pill is available as a quick fix — but should be discussed beforehand with a qualified physician.
Personally, I would opt for a warm cup of milk before resorting to a pill habit. Adapting a routine of reciting krias shema and placing negel vasser (hand washing cup and basin) by her bed for her convenience upon arising in the morning (a segulah for promoting good sleep) should have your daughter enjoying a restful night’s sleep in no time.
Good luck and keep us posted!
Confidential to James P. (Yaakov): Appreciate your thoughtfulness in updating me. I am delighted that Rabbi Herman has been in touch and been able to be of help. May Hashem hearken to your prayers and continue to be at your side in your time of need.