Help. Please

[Bwekfusth]

For the past few weeks my 4 year old son will not sleep. He screams and screams about robots, there are none, we have told him over and over that there are none, nothing is coming to get him, there's nothing to be afraid of, I'm starting to believe he's making it up as I went in there a moment ago to once again say there are no robots, and he started to tell me he was afraid of ALL of his other toys instead. After removing a few of the ones he asked me to, and closing the door, the screaming continued. I don't want to cave and bring him downstairs once again till he falls asleep at 11 as then he will know he can get what he wants with this behaviour. It's not only himself he is affecting here it's his 6 year old brother who shares a room with him. The other night it went on and in till 4am. I don't want to have him in bed with us as I work full time and start very early and I need to sleep, which I can not achieve with a wriggling child wedged in beside me, and again, I do not want to get in to that habit. I just don't know what to do, I can't really stand another night of this.

He may be making it up. He may not be. There is no way to prove that this is completely made up, do you want to risk leaving a terrified child alone scared at bed time?
4 is common for night mares and fears of the dark as their imagination is vivid and can get away from them especially in a dark room with nothing to distract them from weird shapes.
Act as though the fear is real and find ways of making it better (it probably is real).
A night light so that he can see that nothing is moving. Make a monster spray spray it around, talk about how fight monsters. Find a nightly ritual to keep the monsters away. Lots of cuddles and reassurance and patience.

Why don’t you stay with him until he falls asleep?

Thanks for the replies, we have done all the monster zapping etc but it's got to a point where I think is that helping as it's sort of reinforcing the idea that there are actually monsters to zap? It's thrown me slightly as up until now he's been a great sleeper, as for the dark, they go to bed at 7 and it's now light in their room till gone 9. And as for laying with him till he falls asleep - tried, he was still awake at 9 and I have things to do so I gave him a kiss and a cuddle and left and it all started up again. Really hoping this is just a phase as I'm knackered!