Jay Overholts also appears in "Where is Everybody?," "One for the Angels," "A Thing About Machines," "The Odyssey of Flight 33," "Static, "The Jungle" and "Showdown with Rance McGrew."

Wesley Lau was also in "The Fugitive."

Jonathan Harris' most famous role is that of stowaway Dr. Zachary Smith on Lost in Space. Harris would later go on to appear in "The Silence."

This is one of six episodes originally shot on videotape, then transferred to sixteen-millimeter film for broadcast. This was done as a cost-cutting measure.

Arlene Martel was previously seen in "What You Need."

Fredd Wayne also appears in "The Arrival."

Serling wrote this episode based on an anecdote from Bennett Cerf's Famous Ghost Stories (1944).

Nurse: Room for one more, honey.

Opening Narration
Narrator: This is Miss Liz Powell. She's a professional dancer and she's in the hospital as a result of overwork and nervous fatigue. And at this moment we have just finished walking with her in a nightmare. In a moment she'll wake up and we'll remain at her side. The problem here is that both Miss Powell and you will reach a point where it might be difficult to decide which is reality and which is nightmare, a problem uncommon perhaps but rather peculiar to the Twilight Zone.

Liz Powell: I know what I saw. I know what I did.
Doctor: I'll tell you what, Miss Powell. To prove my point, let's try something different.
Liz Powell: Like what?
Doctor: You say it always happens in such pure chronology, that your actions are always the same. Tonight, when you're dreaming, or as you say when you're waking up, don't reach for the glass. See if breaking the routine a bit won't stop it from happening.
Barney Kaminer: Now that sounds like a groovy idea, Doc. Why don't you try it, kitten, huh? Why don't you try it?
Liz Powell: Barney, Barney, will you tell him? When the same thing happens to you for six nights in a row...
Doctor: Overwork, fatigue, tiredness. A nightmare at this point would not be abnormal, Mr. Kaminer. A nightmare in this case would be the normal. Well, Miss Powell, let's see what this evening brings, shall we.
Barney Kaminer: Yeah, well, I gotta be running along, kitten. Now you stay hip to what the doc here is telling you. I'm sure glad to see you feeling, uh, looking so good again.
Liz Powell: Thanks a heap, Barney. You know, you couldn't boost morale if it weighed a quarter of a pound and you had a derrick. Thanks for coming over. You must do it again sometime, only make it next year, will ya.
Barney Kaminer: Ah, kitten baby!
Liz Powell: Get out, will ya, Barney!
Barney Kaminer: Sure, Liz, sure. (Barney leaves)
Doctor: Remember about tonight, Miss Powell. When you feel compulsion to repeat the nightmare, don't do it. Now, relax. Get to sleep. I think we're on our way to recovery.
Liz Powell: We're just delighted that we feel that way.

Liz: Thanks a heap, Barn. You know, you couldn't boost morale if it weight a quarter of a pound and had a derrick.

Closing Narration
Narrator: Miss Elizabeth Powell, professional dancer. Hospital diagnosis: acute anxiety brought on by overwork and fatigue. Prognosis: with rest and care, she'll probably recover. But the cure to some nightmares is not to be found in known medical journals. You look for it under 'potions for bad dreams,' to be found in the Twilight Zone.

Liz is standing towards the elevator with her hand on her face. The camera shot immediately switches to her front view, but her hand is no longer on her face.