I second the advice of the answer from Flummox - you can't control when or where a cat sleeps. It simply is not possible.
Why can't you let her roam the house and sleep when and where she wants?
If this is a case of you wanting your cat to sleep with you in your bed, she will do so if she wants to - not because you want her to.
The key to getting a cat to regard you as a large part of his or her life and to spend time with you, come when you call (or most of the time), sleep next to you, etc. is to give the cat a reason to be near you.
If you provide warmth, comfort, pleasant physical contact, and show that you can be trusted, a cat will do all the things most people want them to do.
All of our cats (we have quite a few) sleep on the bed without us. CeeCee usually sleeps under the covers with my wife. Murphy often sleeps on my arm (I sleep on my left side). Jenny often spends part of the night next to me and most of the other cats sleep on the bed, usually quite close to us.
There are always at least two cats between my wife and myself, and sometimes three or four - we have a queen sized bed but it still gets rather crowed at times.
Most of our cats come when called, most of the time, and some will come to me if I simply motion for them to do so. Murphy will often come to me if I lock eyes with him and raise my eyebrows two or three times - I'm not kidding, that's the sort of close relationship I have with Murphy.
Why do our cats spend time with us, because we provide something that they want, something they need - it really all comes down to TLC.
There should be no reason for your not allowing your cat (what is her name?) to roam the house and sleep where ever she wants, whenever she wants.
You can't force a cat to sleep somewhere, even if you think they are getting sleepy.
It Won't happen.