Hercules - Season 1 - Eps 56: Hercules and the Long Nightmare
We see how the Greek Gods got their position when helping to build Greece. Morpheus' younger brother Phantasos makes a blanket of nightmares to drag through the night sky giving everyone nightmare because he should've been made The God of Sleep instead of Morpheus. The mortals' nightmares start to concern all the Greek Gods including Morpheus. It's up to Hercules and Phil to stop Phantasos' plot in their shared dreams.
About Hercules

Title: Hercules
First Air Date: 1998-08-31
Last Air Date: 1999-03-01
Status: Ended
Rating: 6.8/10 (from 297 votes)
Language: EN
Seasons: 1
Total Episodes: 65
Network: Syndication ABC
Genres: Comedy, Kids, Animation, Action & Adventure
Production Companies: Disney Television Animation
Synopsis
Follow Herc's many labors during the years he spent training on how to be a hero under the tutelage of satyr Phil. Many of the Olympian Gods and Goddesses pay visit to the young hero-to-be and help or hinder him in his new adventures.
Cast

Tate Donovan
Hercules (voice)

French Stewart
Icarus (voice)

Sandra Bernhard
Cassandra (voice)

James Woods
Hades (voice)

Robert Costanzo
Philoctetes (voice)

Robert Stack
Bob (voice)

Diedrich Bader
Adonis (voice)

Matt Frewer
Panic (voice)

Corey Burton
Zeus (voice)

Frank Welker
Pegasus (voice)