As usual, others before me have given you lots of good advice.
My comment may seem flippant at first, but I really do mean it and offer it in a friendly tone.
I think whatever boat you buy (cat or mono) you will learn to sleep on it as a good skipper/owner should.
That means you will become "attuned" to YOUR boat and its motions and sounds. Whether the boat is sitting still (relatively speaking) or rocking or moving a bit on the anchor
, ALL of those things will become "messages" to you that will help you stay safer and eventually learn to rest easier.
But, unless you are living in a marina, and assuming you are at anchor
(on the hook), you will want to sleep and also be aware
when something wakes you (a new motion or sound). Those things signal that it is time to check something, such as whether your anchor is dragging, or the wind is picking up, etc.
I am a relatively light sleeper. But, the fresh air and the day's activity (exercise comes with a boat) AND the motion of the boat on the water
makes one sleep nicely, unless there is something to worry about, such as approaching bad weather
Sleeping on a boat can be like a baby rocked to sleep by a mother.
Just make sure you learn to tie off your halyards to prevent them from slapping the mast
all night! That sound will drive anyone crazy!
Still can't sleep?
Do some boat maintenance
. Or...There is always the old salts sleeping aid, a bottle of rum
What would I buy?
The best available boat within my budget
, mono or cat.
Would I prefer a cat?
Only if it is nicer than the mono at the same price point.
Good luck on your future boat decision and your change of domicile.
Now here is a serious idea that may help you:
Go to Youtube. Search for sound recordings of a sailboat. Some of these are 8 hours long (see my link below). Play that at home when you go to sleep. Get your brain accustomed to the sounds of boats and wind in the rigging.
You might even find you sleep better on land while listening to these sounds, as is often reported by the people who listen to these recordings. They can be soothing sounds.
My favorite that I have found is: http://youtu.be/ZkHeztKuY3g?list=PLX...P8XjUnfM-H-sVu
It is also part of my playlist of music
for sailors (which can get you in the mood to go sailing or dreaming about boats). My playlist is here: