Somnosian Empire

The Somnosian Empire was the military force of the Somnosians. They were able to spread across the 18th quadrant by putting the occupants of every planet they reached to sleep, offering them no resistance when they invaded. A Somnosian invasion force reached Earth and put the planet's inhabitants to sleep. After the Twelfth Doctor awoke the humans and they showed up to fight the Somnosians, the invasion force retreated from Earth. (COMIC: Beauty Sleep)