Is there a simple way to change the amount of sleep time required for a level up?

I didn't know there was a time required. Just sleep of any duration.

Do you want to establish a minimum? And how? Just not allow sleeping for less, or the more complex (impossible?) suppressing the level-up?

I think the former could be accomplished by having a menumode script choose the cancel option for you if the duration isn't enough. I'm not sure if a script could reduce the skill levels below the threshhold and re-raise them after the sleep to do the suppression.

Hmm, for some reason I always thought you had to sleep a minimum of 3 hours for the level up sleep. Thank you for the advice, but I don't think I'll want to get that far into changing it. Perhaps there's a leveling mod that can suppress levels or at least slow them down by quite a bit.

There is an .ini tweak to remove the sleep requirement completely. Find bInstantLevelUp= and set it to 1. You will get the level up screen as soon as you get your tenth skill increase. Although it sounds like you want to do the opposite.

No time specifically needed. One hour or ten, doesn′t matter