NEPA Known World
The BECMI rules are mum on the way natural healing occurs. The older rules and the RC rules conflict. Therefore, we will house rule it:
Characters regain 1 hit points for every night’s rest. This rest must be equivalent to the rest needed to regain spells. A wandering monster attack in the middle of the night will not preclude healing but characters must get a minimum of six hours of sleep to achieve the healing.
If a character is on complete bed rest (not adventuring or resting overnight), s/he will regain 1d4+1 hit points per day. Complete bed rest means no more strenuous activity then carefully going up a flight of stairs or fixing and eating a bowl of oatmeal.