sleeping in the middle of the day - urgent

my daughter is 6.5 she is usually full of energy and a happy one. in the past 2 weeks she has been falling asleep in the middle of the day. last night she fell asleep in the middle of school i am taking her to the doctor's tomorrow but would like to know beforehand: what can be the cause of this what tests should i ask the doctor to perform any other suggestions toda

איילת שלום לא יודע - בדקו את בלוטת התריס ואולי שווה גם לבדוק למחלת הנשיקה וכמובן אנמיה. בכל מקרה - בדיקת רופא ואולי אף נוירולוג. (אגב היא ישנה טוב בלילה ?) בברכה

thanks. she sleeps well at night. sometimes she falls asleep a bit late but thathas been the case for a few years now, and never was she so "out" in the middle of the day