A 14 y.o. girl got a bad mark at the lesson of math as well as teacher's reprimand that made her cry for a long time. At the end of the lesson she suddenly lost consciousness and fell down. Objectively: skin is of pale pink colour, Ps- 100 bpm, satisfactory, AP- 110/70 mm Hg. Eyelids are closed and don't give away to the tries of their opening. There are no evident injuries. What is the provisional diagnosis?