Hmmmm... I've never had that problem, but that's probably because we train them to lay down from the time they are old enough to get up... (as soon as they can pull up in their crib, a parent sits in there and gently pushes them back down, saying "Lay"...which takes up to a week to teach, but once they get it, they obey till they hit preschool stage, after which time it's no longer necessary. It helps the babies go to sleep much faster, and it keeps the toddlers in their toddler bed.
BUT, if this were my child, here's what I'd do.
I'd recommend getting a very very very good book (or a whole stack of 'em, if you're a fast reader like I am), and pulling a chair into his room, getting comfy, and reading in there 'till he falls asleep. None of the caressing stuff...just sitting nearby (with a spanking spoon in hand) and being absorbed in your book. No talking to him, other than a quick smile and saying, "No talking now, honey, it's bedtime" anytime he tries to initiate conversation.
When he gets up, you hop up and dole out a quick swat, and he hops back to bed, and back to your book you go.
The key on your part is to remain totally calm (even if you are just faking it!). If he wants to lay there and throw a fit, just ignore him. (
I don't think it's good to allow a child to throw a fit, but I think it's good to work on just one thing at a time here--you can deal with fits at a later date).
This way you have a few things fixed:
Number One: you are right there, to deal with him getting out of bed THE SECOND he starts doing it. That's important. 100% consistancy is the cardinal rule of training!
Number Two: You
are in the room--he can be comforted by your presence, if the issue really is fear of some sort.
Number Three: You are able to be consistant about the rule of staying in bed, but since you are comfortable and prepared to spend a couple hours in there if need be, until he chooses to obey, you are going to be able to keep your cool instead of going nuts. That is very very very important. When you blow a gasket (heehee), they learn that THEY have won. But it's not a kind of 'winning' that either side benefits from.
You need to remain totally calm and in control...which shows him that you WILL solve this issue and that you will stand your ground longer than he'll stand his. And children want to know that--if you're willing to stand your ground. It makes them feel protected and secure when they know you WILL. Even though they also enjoy challenging you to see if you really will! Heehee...
So having a good book and the mental preparation--the realization that you are probably going to spend a long time in that room for a week or two until he starts getting the hang of the new regime!--will go a LONG way in ensuring you retain your mental sanity!
I'd check out this site below for more suggestions, and really really really really really really really would recommend their parenting book to you. I think it will answer a LOT of your questions. (It's cheap, too)!

There's a
reason we have such a happy fun home with so many youngsters, and this little treasure trove of a parenting book is one of them! (
Not that we think their word is "gospel," because it's human advice so it's not going to be perfect, but a lot of their practical ideas we've found to be just plain awesome! They are HUGE lovers of their children, advocating a house full of joy and laughter...and yet also taught them to obey ALWAYS, and I love the gentle combination of the two).
http://www.NoGreaterJoy.org
Hope this helps some!
Blessings,
Molly