NWN lets you spend about 15 seconds sitting on the floor and calls this a good night’s rest. As far as the engine is concerned, you can do this pretty much whenever you want, as often as you want. You can cast spells at a monster, go into another room that they can’t get to, rest, then pop back out and cast the same spells over again.
Obviously, this is pretty stupid, and we won’t be doing things that way. Until I put scripts in to change resting behavior, please refrain from resting until I explicitly tell you you can. This will only be in situations where the party has the opportunity to get a decent night’s sleep in relative comfort, and if you click the rest button, it is implied that your character will be asleep until morning or unless roused.
Currently, resting refills HP to full. Depending on the conditions, I might manually reduce your health after the rest is over – and once I re-script resting, the HP recovery will probably be reduced.
Also, those of you who are casters, don’t forget that resting contains an implied spell preparation. There’s a spellbook button in the upper right hand corner of the GUI where you can pick your spells before resting.