Voir Adventures of Sonic the Hedgehog, Season 1, Vol. 1 - Episode 27

Professor Von Schlemmer (from Too Tall Tails) has created a machine which brings dreams to life. When Robotnik hears about it, he forces the Professor to alter the machine so that nightmares come to life, and unleashes a Bogey Man on the Mobius population. With the Professor's help, Sonic goes into the World of Dreams to find the answer to the problem. Sonic makes Robotnik go to sleep and uses Tails' nightmare monster to chase the Bogey Man back into Robotnik's dreams.