Hello doctor, my son is 4 year old going to preschool. He is very active and everything is normal. But for the last one week, everyday during bedtime as soon as I switch off the lights and when he lays down, he says his head is spinning but he will sleep in 5-10 minutes. Other times he is very normal and he doesn't say it. Even when I ask him in the morning when gets up he says no spinning. I thought he feels sleepy so he says like that. Is there anything to be worried?