Baldur's Gate II: Shadows of Amn Tips

Safe Sleeping
Keep in mind that just because an area appears safe doesn't mean it will stay safe for long. While it is unlikely you will encounter a roaming enemy worth worrying about, many enemies will attack you while you rest, sapping up your strength and forcing you to try and rest again if you want all your mage spells ready for combat.

It's best to to sleep in a town, especially in an inn... the room does not need to be expensive.