Why do kids wake up in the middle of their sleep screaming and crying?

When my toddlers get too tired during the day, they usually wake up in the middle of the night and scream. Too overwhelmed with their activities maybe.

I notice that sa baby ko lalo na pagsobrang saya sa paglalaro...

Nananaginip or binabangungot po sila kapag ganyan.

They possibly having a bad nightmare.