5 Hours sleep would be a normal night for me
But anyway... the solution of putting an indoor cat that hates the outdoors, outdoors to solve a yowling problem is non-sensical. I mean basically at that point it's kind of an expulsion of your cat, against her will. And it's going to greatly shorter her life. Who would that benefit? You may as well rehome her at that point.
Taking her to the vet is not a bad idea when there is a radical behavior change, although generally when a cat is hurting from something they go the other way, and become reclusive and with less energy.
Questions:
1. How is she set up for the night? Does she have access to your room? Does she have food and water? What sort of sleeping options does she have?
2. What is the temperature like in your house right now?
3. When she is yowling, what is she doing? Is she looking out a window? Is she sitting with her toys wanting to play? Is she staring at an empty food dish?
4. What sort of noises might be outside your home at the time she is yowling? Are there other cats outside?
This is obviously a problem that a lot of Bengal owners have or do suffer from. One solution to get your cat to sleep better is to change your routine a bit (if necessary) to make sure there is a long hard playtime, followed by a meal, then bed time.