Which area of the brain influences sleep and dreaming?

When researchers destroy the reticular formation of rats via deep lesioning, the rats

The _____ stimulates the upper part of the brain, keeping people awake and alert.

Karu is two months old and cannot yet sit upright on his own. Karu's inability to sit on his own is most likely due to which of the following?

Which area of the brain influences sleep and dreaming?