USD/JPY overnight moves?

I am relatively new to Forex. I have been following the USD/JPY for the past few months and noticed there seems to regularly be more consistent, bigger moves during the overnight hours; 00:00 - 7:00, more particularly, 03:00-07:00. Does anyone know why this is occurring?

Yes some of the biggest moves in the currency pairs are between 2-4am EST this is because Frankfurt opens at 2:00am and London at 3:00 these are some of the biggest markets.

EDIT: Forgot to mention Tokyo closes at 4am as well so you have 2 markets opening and 1 closing, this creates a lot of action.