Can you not dream in a night?

Yes you, can have nights when you can't dream. You fall asleep regularly and instead of dreaming, it is blank. Time goes by the same, you don't notice it.

No, one cannot sleep without some level of dreaming taking place. Studies done in sleep labs with brain imaging tools indicate that everyone dreams during each period of sleep, whether those dreams are remembered or not. If one sleeps soundly and does not wake up while a dream is occurring, it is very common not to remember any dreams. See attached link below for further information.