The do sometimes get screens at night, but I'm a big stickler about no blue light after 9pm normally (although now that's no blue light after midnight).

I've changed out bulbs throughout the house so that we can light the whole house in 1850K light at night, and all screens use some sort of red-shifting (screens that can't redshift like TVs get turned off).

But you're right, if they get too much screen is does keep them up longer. But even without the blue screens they will stay up playing with toys under 1850K lights until the very AM hours!