Pam, I have just read the topic you mentioned and I was amazed at the fact people seemed to be assuming cats are day creatures! 4 Feline house was the first to aknowledge that cats are nocturnal - dawn and dusk are prime hunting times for our feline friends.

Fortunately mine love sleeping and can freely come and go from my bedroom as they please - this stops me going crazy as one of them knows how to open doors (depending on the handle) and they both have a yeoowwl that not only wakes me but I'm sure the neighbours stir as well

Allison I assume that Heidi is an indoor cat that is not allowed in your bedroom at night?
How long has Heidi been doing this and does he ever give up or do you find that you have to get up to stop him? You could try getting up as soon as you hear her and growl her followed by locking her in the laundry for the rest of the night. She will learn quickly to associate her midnight calls on your room with being stuck in the washhouse for the rest of the night very quickly. This may be a nuisance to start with but will probably be worth the effort.

I must say that I would stongly encourage any method above sleeping tablets as they do not provide an animal (or human) proper rest due to the fact sedatives deprive the brain of REM during sleep which is what rests our brain. You would probably find you'd end up with a very tetchy animal with a drug addiction...

Let us know how it goes, and good luck!