I’m assuming you’re a girl… as ‘wet dreams’ are far more common in guys, but yes, it is possible. However it’s more likely that you’re just feeling a drop in arousal which can happen naturally. It might be that you just need to build up more slowly, let it grow over a few days.
Or you could try something more drastic, try a dildo in you overnight – a pair of panties or two will usually keep it in place, if not search this blog for the crotch rope instructions. Just make sure if you use something in you it’s safe and clean, you don’t want to be getting toxic shock.
And beyond the dildo it might be you have other things that really turn you on, perhaps nice lingerie or nightwear – so sleep in it, or sleeping naked rather than clothed. Or if you haven’t tried a butt plug then you might find that’s something that really keeps you aroused and you can wear overnight.
Try some of those and hopefully they’ll stop you dropping off the cliff!